Table of contents
by Fr. Thomas Hopko
Spirituality in the Orthodox Church means the everyday activity of life in communion with God. The term spirituality refers not merely to the activity of man’s spirit alone, his mind, heart and soul, but it refers as well to the whole of man’s life as inspired and guided by the Spirit of God. Every act of a Christian must be a spiritual act. Every thought must be spiritual, every word, every deed, every activity of the body, every action of the person. This means that all that a person thinks, says and does must be inspired and guided by the Holy Spirit so that the will of God the Father might be accomplished as revealed and taught by Jesus Christ the Son of God.
... whatever you do, do all to the glory of God (1 Cor 10:31).
Doing all things to the glory of God is the meaning and substance of life for a human being. This “doing” is what Christian spirituality is about.
Christian spirituality is centered in God; in fact, its very goal is communion with God, which is attainable through the accomplishment of His will. To be what God wants us to be and to do what God want us to do is the sole meaning of our human existence. The fulfillment of the prayer “Thy will be done” is the heart and soul of all spiritual effort and activity.
In the Old Testament law, it is written:
I am the Lord your God; consecrate yourselves therefore, and be holy, for I am holy (Lev 11:44).
In the New Testament, the first letter of Saint Peter refers to this fundamental command of’ God.
... as He who called you is holy, be holy yourself in all your conduct; since it is written, “You shall be holy, for I am holy”(1 Pet 1:16).
That human beings should be holy by sharing in happiness of God Himself is the meaning of union with God. All are “called to be saints” (Rom 1:7) by becoming “partakers of the nature of God” (2 Pet 1:1). This is what Jesus meant when He said in Sermon on the Mount, “You, therefore, must be perfect, as your heavenly Father is perfect” (Mt 5:48).
The teaching that man must be holy and perfect like God Himself through the accomplishment of the will of God is the central teaching of the Orthodox Christian faith. This teaching has been stated in many different ways in the Orthodox spiritual tradition. Saint Maximus the Confessor (7th Century) said it this way: “Man is called to become by divine grace all that God Himself is by nature.” This means very simply that God wills and helps His creatures to be like He is, and that is the purpose of their being and life. As God is holy, man must be holy. As God is perfect, man must be perfect, pure, merciful, patient, kind, gentle, free, self-determining, ever-existing, and always, for eternity, the absolute superabundant realization of everything good in inexhaustible fulness and richness… so man must be this way as well, ever growing and developing in divine perfection and virtue for all eternity by the will and power of God Himself. The perfection of man is his growth in the unending perfection of God.
Christian spirituality is centered in Christ. Jesus Christ is the divine Son of God who was born as a man of the Virgin Mary in order to give man eternal life in communion with God His Father.
In Jesus Christ “the whole fulness of deity dwells bodily” (Col 2:9). In Him is the “fulness” of “grace and truth” (Jn 1:16-17) and “all the fulness of God”(Col 1:19). When one sees and knows Jesus, one sees and knows God the Father (Jn 8:19, 14:7-9). When one is in communion with Jesus, one is in abiding union with God (cf. Jn 17, Eph 2, Rom 8, 1 Jn 1).
The goal of human life is to be continually “in Christ.” When one is “in Christ,” according to St John, one does God’s will and cannot sin.
You know that He (Jesus) appeared to take away sins, and in Him there is no sin. No one who abides in Him sins; no one who sins has either seen Him or knows Him. ...he who does right is righteous, as He is righteous. ...No one born of God commits sin; for God’s nature abides in him, and he cannot sin because he is born of God. By this it may be seen who are the children of God, and who are the children of the devil; whoever does not do right is not of God, nor he who does not love his brother (1 Jn 3:4-10).
Jesus Christ is “the Way, the Truth and the Life”(Jn 14:6). He speaks the words of God. He does the work of God. The person who obeys Christ and follows His way and does what He does, loves God and accomplishes His will. To do this is the essence of spiritual life. Jesus has come that we may be like Him and do in our own lives, by His grace, what He Himself has done.
Truly, truly I say to you, he who believes in me will also do the works that I do; and greater works than these will he do, because I go to the Father (Jn 14:12)
The Holy Spirit
A person can abide in Christ, accomplish His: commandments and be in communion with God the Father only by the presence and power of the Holy Spirit in his life. Spiritual life is life in and by the Holy Spirit of God.
If you love me (says Christ), you will keep my commandments. And I will pray the Father, and He will give you another Comforter to be with you forever, even the Spirit of Truth, whom the world cannot receive, because it neither sees Him nor knows Him; you know Him, for He dwells with you and will be in you (Jn 14:15-17). When the Spirit of Truth comes, He will guide you into all the truth. ...He will glorify me, for He will take what is mine and declare it to you. All that the Father has is mine… (Jn 16:12-15).
The Holy Spirit proceeds from the Father and is sent into the world through Christ so that human persons an fulfill God’s will in their lives and be like Christ. The spiritual fathers of the Orthodox Church say that he Holy Spirit makes people to be “christs,” that is, the “anointed” children of God. This also is the teaching of the apostles in the New Testament writings:
But you have been anointed by the Holy One and you know all things… and the unction [chrisma] you have received from Him abides in you… His anointing teaches you about everything and is true and is no lie, just as it has taught you, abide in Him. [...] And by this we know that We abides in us, by the Spirit which He has given us. [... ] By this we know that we abide in Him and He in us, because lie has given us of His own Spirit (1 Jn 2:20-27, 3:24, 4:13).
This teaching of Saint John is the same teaching as that of Saint Paul.
... God’s love has been poured into our hearts through the Holy Spirit which has been given to us. [...] Any one who does not have the Spirit of Christ does Christ does not belong to Him. But if Christ is in you, although your bodies are dead because of sin, your spirits are alive because of righteousness. If the Spirit of Him who raised Jesus from the dead dwells in you, tie who raised Christ Jesus from the dead will give life to your mortal bodies also through His Spirit which dwells in you… for if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live. For all who are led by the Spirit of God are sons of God (Rom 5:5, 8:1ff; cf. 1 Cor 2, 6, 12-14; Gal 5).
It is the classical teaching of the Orthodox Church, made popular in recent times by St Seraphim of Sarov (19th c.), that the very essence of Christian spiritual life, the very essence of life itself, is the “acquisition of the Holy Spirit of God.” Without the Holy Spirit, there is no true life for man.
In spite of our sinfulness, in spite of the darkness surrounding our souls, the Grace of the Holy Spirit, conferred by baptism in the name of the Father and the Son and the Holy Spirit, still shines in our hearts with the inextinguishable light of Christ… and when the sinner turns to the way of repentance the light smooths away every trace of the sins committed, clothing the former sinner in the garments of incorruption, spun of the Grace of the Holy Spirit. It is this acquisition of the Holy Spirit about which I have been speaking. ...(St Seraphim of Sarov, Conversation with Motovilov).
Man, according to the scriptures, is created “in the likeness of God” (Gen 1:26-27). To be like God, through the gift of God, is the essence of man’s being and life. In the scriptures it says that God breathed into man, the “breath [or spirit] of life” (Gen 2:7). This divine teaching has given rise to the understanding in the Orthodox Church that man cannot be truly human, truly himself, without the Spirit of God. Thus Saint Irenaeus (3rd c.) said in his well-known saying, often quoted by Orthodox authors, that “man is body, soul, and Holy Spirit.” This means that for man to fulfil himself as created in the image and likeness of God—that is, to be like Christ who is the perfect. divine, and uncreated Image of God—man must be the temple of God’s Spirit. If man is not the temple of God’s Spirit, then the only alternative is that he is the temple of the evil spirit. There is no middle way. Man is either in an unending process of life and growth in union with God by the Holy Spirit, or else he is an unending process of decomposition and death by returning to the dust of nothingness out of which he was formed, by the destructive power of the devil. This is how the Orthodox spiritual tradition interprets the “two ways” of the Mosaic law:
I call heaven and earth to witness against you this day, that I have set before you life and death, blessing and curse, therefore choose life that you and your descendants may live, loving the Lord, obeying His voice and cleaving to Him, for that means life to you(Dt 30:19-20).
It is this same teaching that the Apostle Paul gives in his doctrine of the “two laws” at work in the life of man.
For I delight in the law of God in my inmost self, but I see in my members another law at war with the law of my mind and making me captive to the law of sin which dwells in my members. [...] For the law of the Spirit of life in Christ Jesus has set me free from the law of sin and death. [...] For those who live according to the flesh set their minds on the things of the flesh, hut those who live according to the Spirit set their minds on the things of the Spirit. To set the mind on the Spirit is life and peace (Rom 7:14-8:17).
Every human being is confronted with these two possibilities, ultimately the only two possibilities of human existence. Either a person chooses life by the grace of God and the power of the Spirit—the “abundant” and “eternal life” given by God in creation and salvation through Jesus Christ—or the person chooses death. The whole pathos of human existence consists in this choice, whether a person is aware of it or not. Christian spiritual life depends on the conscious choice of the “way of life.” To “choose life” and to walk in the “way of life” is the way that man shows himself to be in the image and likeness of God.
Sin, according to the scriptures is “lawlessness” and “wrongdoing” (1 Jn 3:4, 5:17). To do wrong and to be unrighteous is to sin. In the Greek language the word sin originally meant “missing the mark,” that is, moving in the wrong direction, toward the wrong aims and goals. It means choosing and going in the way of death, and not the way of life.
There are many scriptural expressions for sin, all of which presuppose a primordial rightness and goodness. The word fall indicates a movement down and away from an original high and lofty state. The word stain reveals that there was once an original purity that has been defiled. The word transgression means a movement against that which is primarily right. The word guilt reveals prior innocence. The words estrangement and alienation indicate that one was first “at home,” living in a sound and wholesome condition. The word deviation means that one has gone off his original way.
There are no words for sin which do not reveal in their very utterance that sin is an unnatural state of man, a condition brought about by the destruction, distortion, and loss of something good which was originally present. Every sin and wickedness exists only because man’s being and life are naturally positive and good. Every evil and sin act only as “parasites’’ on that which is primarily perfect and whole. Thus, in the Orthodox tradition, sin is not considered to be a normal and natural part of human being and life. To be human and to be a sinner is contradictory. Rather, to be truly human is to be righteous, pure, truthful, and good. Spiritual life, in this sense, consists of only one thing: not to sin. Not to sin is to be like God and His Son Jesus Christ. It is the goal of human life.
Everyone who commits sin is guilty of lawlessness; sin is lawlessness. You know that Christ appeared to take away sins, and in Him there is no sin. No one who abides in Him sins; no one who sins has either seen Him nor known Him. Little children, let no one deceive you. He who does right is righteous, as He is righteous. He who commits sin is of the devil; for the devil has sinned from the beginning. The reason the Son of God appeared was to destroy the works of the devil. No one born of God commits sin; for God’s nature abides in him, and he cannot sin because he is born of God. By this it may be seen who are children of Cod, and who are children of the devil; whoever does not do right is not of God, nor he who does not love his brother (1 Jn 3:4-10).
Not to sin is the goal of human life. But in fact all people do sin. It is for this reason that the possibility to be freed from sin and to overcome sin comes through the saving work of Christ, who forgives the sins of the world.
If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, He is faithful and just, and will forgive our sins and cleanse us from all unrighteousness. If we say we have not sinned, we make Him a liar, and His word is not in us. My little children, I am writing this to you so that you may not sin; but if any one does sin, we have an advocate with the Father, Jesus Christ the righteous; and He is the expiation for our sins, and not for ours only but also for the sins of the whole world. ...by this we may be sure that we are in Him: he who says he abides in Him ought to walk in the same way in which He walked (1 Jn 1:8-2:6).
The scriptures and the lives of God’s saints bear witness to the existence of the devil. The devil is a fallen bodiless spirit, an angel created by God for His service and praise. Together with the devil, are his hosts of wicked angelic powers who have rebelled against the goodness of God and seek to pervert and destroy God’s good creation.
How are you fallen from heaven, O Lucifer, Day Star, son of Dawn!
And the angels which did not keep their own position but left their proper dwelling have been kept by him in eternal chains in the nether gloom until the judgment of the great day. ... (Jude 6, Cf. 2 Pet 2:4) . ...the devil and satan, the deceiver of the world—he was thrown down to the earth, and his Ãºangels were thrown down with him (Rev 12:9) .
In the New Testament the Lord Jesus speaks of the devil whom He called him “prince of this world” (Jn 12:31, 14:30, 16:11) in this way:
He was a murderer from the beginning, and has nothing to do with the truth because there is no truth in him. When he lies, he speaks according to his own nature, for he is a liar and the father of lies (Jn 8:44).
The devil and his multitude of evil spirits, “the principalities… the powers… the world rulers of this present darkness… the spiritual hosts of wickedness in heavenly places”(Eph 6:12) war against man seeking to destroy him by ensnaring him in sin.
Your adversary, the devil, prowls around like a roaring lion seeking someone to devour (1 Pet 5:8).
Christ has destroyed the power of the devil. He came into the world precisely for this reason. If one is “in Christ” he is led out of temptation and delivered from the evil one. If one is in Christ, the evil, who is also called Satan, which means the Adversary who “disguises himself as an angel of light” (2 Cor 11:14), cannot deceive or harm him. To be victorious over the alluring and deceiving temptations of the devil is the goal of spiritual life.
The World and the Flesh
In the scriptures and in the spiritual tradition of the Church, the expression “the world” has two different meanings. In the first, “the world” is the expression of all of God’s creation. As such it is the product of God’s goodness and the object of His love.
According to the scriptures, God creates the world and all that is in it. He creates the heavens and the earth as the declaration of His glory (Ps 18:1). He creates an living things, crowned by the formation of man in His own image and likeness. According to the scriptural record, God called His creation "good… very good” (Gen 1:12, 18, 25, 31). And according to the Gospel, Christ has come as the “savior of the world”(Lk 2:11, Jn 4:42).
For God so loved the world that He gave His only Son, that whoever believes in Him should not perish but have eternal life. For God sent His Son info the world, not to condemn the world, but that the world might be saved through Him (Jn 3:16-17).
In addition to this positive scriptural understanding of “the world,” there is also a negative use of the expression which has caused confusion about the proper understanding of Christian faith and life. This negative use of the term “the world” is presented not as God’s object of love, but as creation in rebellion against God. Thus Christ spoke:
If the world hates you, know that it has hated me before it hated you. If you were of the world, the world would love its own; but because you are not of the world, but I chose you out of the world, therefore the world hates you (Jn 15:18-19; Cf. Jas 4:4).
Saint John continues to speak of the enmity between Christ and “the world” in his first letter where he gives the following commandment to Christians.
Do not love the world or the things in the world. If anyone loves the world, love for the Father is not in him. For all that is in the world, the lust of the flesh, the lust of the eyes and the pride of life, is not of the Father but is of the world. And the world passes away and the lust of it; but he who does the will of God abides forever (1 Jn 2:15-17).
The same ambiguity as that concerning “the world” exists with the expression “the flesh.” In some instances, the term flesh is used in a positive sense meaning the fulness of human existence, man himself. Thus it is written about the incarnation of Christ that the “Word became flesh and dwelt among us, full of grace and truth” (Jn 1:14). It is also written that on the day of Pentecost, God poured out His Holy Spirit “on all flesh”(Acts 2:17, Joel 2:28). The word “flesh” in this sense carries no negative meaning at all. Rather it is the affirmation of the positive character of created material and physical being, exemplified by Christ who “became flesh” and commands men to “eat of my flesh” (John 6:53-56).
In the scriptures again, particularly in the writings of Saint Paul, the expression “the flesh” is used in the same negative way as “the world.” It is employed as the catchword for godless and unspiritual existence.
For those who live according to the flesh set their minds on the things of the flesh, but those who live according to the Spirit set their minds on the things of the Spirit. To set the mind on the flesh is death, but to set the mind on the Spirit is life and peace. For the mind that is set on the flesh is hostile to God; it does not submit to God’s Law, indeed it cannot please God (Rom 8:5-8).
Here, for Saint Paul, the term “flesh” is not a synonym for man’s body which is good, and the apostle makes this perfectly clear in his writings.
The body is not meant for immorality, but for the Lord, and the Lord for the body. [...] Do you not know that your bodies are members of Christ? [...] Do you not know that your body is a temple of the Holy. Spirit within you, which you have from God? You are not your own; you were bought with a price. So glorify God in your body(1 Cor 6:13.20).
In the spiritual tradition of the Church the ambiguity about “the world” and “the flesh” is treated carefully. It has been explained without confusion by the spiritual teachers and proclaimed clearly in the Church’s sacraments. God’s good creation is not evil. Material existence is not evil. Man’s fleshly body is not evil. Only sinful passions and lusts are evil. They are evil because they treat the created world and the fleshly body of man as ends in themselves, as objects of idolatrous adoration and godless desire. They are evil because, as St Augustine puts it, they. express the “worship of the creature rather than the Creator.”
By nature the soul is without sinful passion. Passions are something added to the soul by its fault… The natural state of the soul is luminous and pure through absorbing the divine light…
The state contrary to nature… is found in passionate men who serve passions.
When you hear that it is necessary to withdraw from the world… to purify yourself from what is of the world, you must understand the term world. “World” is a collective name embracing what are called passions. When we speak of passions collectively, we call them the world. ...the world is carnal life and minding of the flesh(St Isaac of Syria, 6th c., Spiritual Training).
The new and abundant life given by God to man through Christ and the Holy Spirit in creation and redemption is the life of the Christian Church. The life of the Church is the life originally willed for man and his world by God. It is the life of God Himself originally given in creation. It is the spiritual life.
One should not think of the spiritual life of the Church as some particularly special kind of “religious life” different from life itself as we have received it in our creation by God. There are not “two lives,” one “natural” and one “religious.” There is only one life that is real, genuine and true. It is life with God, the life of the Church. Any other life is not life at all: it is the way of death.
What differentiates the life of the Church from the life of “this world,” also called life “according to the flesh,” is only evil and sin. Everything positive is created life, which God has called “good… very good,” is what is saved and sanctified in the life of the Church. Only falsehood and wickedness are excluded—certainly—not creation itself.
In the Orthodox tradition, the Church is called the Kingdom of God on earth, “the re-creation of the world” (Saint Gregory of Nyssa, 4th c., On the Canticles). In the New Testament it is also called the “new creation” (2 Cor 5:17), the Body and Bride of Christ Himself (Rom 12:5; 1 Cor 12:27; Eph 5:23ff; Rev 21:1ff).
... God has put all things under the feet of Christ and has made Him the head over all things for the Church, which is His body, the fulness of Him who fills all in all (Eph 1:22-23).
The Apostle Paul also refers to “the household of God, which is the church of the living God, the pillar and bulwark of the truth” (1 Tim 3:15).
Genuine life, true and real life in perfection and abundance, is found only in the Church of Christ. People who are not formally in the Church are living truly and genuinely only to the extent that they follow the law of God “written on their hearts” by the Spirit of God in creation (Rom 1:12-16), which is the same law clearly revealed and given in Christ and the Church. And those people who are formally members of the Church are living truly and genuinely only to the extent that they actually live the life of the Church. For the sad fact exists that one may be formally a member of the Church and still live according to the law of the: flesh, the law of sin and death, and not of Christ. The spiritual life, therefore, consists in actually living the life of the Church.
The spiritual life of the Church is given to men in the sacraments. The sacraments are called the holy mysteries, and the entire life of the Church is considered to be mystical and sacramental.
The new life in Christ, the genuine life of God, is given to man in baptism, the new birth and new creation of man in Christ by the Spirit of God. In baptism the person who rejects Satan and all of his evil works and accepts Christ and the gift of eternal life, dies and rises again with Jesus to “newness of life.”
Do you not know that all of us who have been baptized into Christ Jesus were baptized into His death? We were buried therefore with Him by baptism into death, so that as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life. [...] So you also must consider yourselves as dead to sin and alive to God in Christ Jesus (Rom 6:3-11; Cf. also Col 2-3, Gal 3).
The new life in Christ Jesus given in baptism—a perpetually dying and rising daily with Jesus—is made possible in man by “the seal of the gift of the Holy Spirit” in the mystery of chrismation (Cf. 2 Cor 1:22, Eph 1:13). Chrismation follows baptism, and is essentially connected to it, as the Holy Spirit comes with Christ, Pentecost comes with Easter, and life comes with birth. There is no new life in the new humanity of divine childhood in Jesus without the life-creating Spirit of God. It is the Holy Spirit in chrismation who makes possible and powerful the spiritual life into which men are born in Christian baptism.
The new life in Christ and the Holy Spirit in the Church is nourished and sustained in the mystery of the eucharist—Holy Communion. The “mystical supper of the Son of God” is the center of the spiritual life. For Christians there is no life at all without it:
I am the bread of life… if any one eats of this bread, he will live forever; and the bread which I shall give for the life of the world is my flesh. Truly, truly I say to you, unless you eat the flesh of the Son of Man and drink His blood, you have no life in you; he who eats my flesh and drinks my blood has eternal life, and I will raise him up on the last day. For my flesh is food indeed and my blood is drink indeed. He who eats my flesh and drinks my blood abides in me and I in him. As the living Father sent me, and I live because of the Father, so he who eats me will live because of me… he who eats this bread will live forever (Jn 6:32ff).
When a person falls away from the life of God in the Church, he or she may be reunited to Christ by the mystery of reconciliation through penitential confession. The abundant mercy of God abides in the Church by the presence of Christ, and the Lord who “desires not the death of a sinner” but that he might “turn from his wickedness and live” (Ez 18:32, 33:14) will forgive those who come to Him in repentance (Cf. Jn 6:37). Continual repentance for sin is a central element in the spiritual life of men who choose life in God, but continue, inevitably, to sin.
If we say we have no sin, we deceive ourselves and the truth is not in us. If we confess our sins, Christ is faithful and just, and will forgive our sins and cleanse us from all unrighteousness. If we say we have not sinned, we make Him a liar and His word is not in us(1 Jn 1:8).
In this life still bound by the sin of the world, man inevitably suffers and dies. His outward nature is wasting away while his new nature in Christ is being perfected. The mystery of the anointing of man’s suffering soul and body is the sanctification of man’s “perishable nature” that his “mortal nature” might “put on immortality” (l Cor 15:51ff). Through holy unction a person is given the grace of the Spirit to make his suffering and death an act of victory and life.
If we have died with Him, we shall also live with Him; if we suffer, we shall also reign with Him… (2 Tim 2:11; Cf. Jas 4:13ff).
In this life as well, God has created human beings in His divine image and likeness as male and female. The union in love between one man and one woman forever is the created expression of the perfect love of God for His creatures. The mystery of marriage is the human image of the “great mystery” of “Christ and the Church” (Eph 6:21-33). In the sacrament of marriage, human love is made eternal and divine by the grace of Christ’s Spirit. There is no parting in death, but fulfillment in the Kingdom of God.
All of the sacramental mysteries of the Church are effected in the Church through the sacrament of the ordained priesthood. The bishops and priests are the ministers within the community who guarantee the reality of the mystical life of the Church in all times and places. Through the ordained ministers within the communion of the Church, Christ Himself is present and powerful in the fullness of His saving activity.
The Kingdom of God
God’s gift of eternal life in Christ and the Holy Spirit is the Kingdom of God. Jesus has brought the Kingdom of God to the world through the Spirit in the Church. Spiritual life is life—already now—in the Kingdom of God.
Fear not, little flock, for it is your Father’s good pleasure to give you the kingdom. Sell your possessions and give alms; provide yourselves with purses that do not grow old, with a treasure in the heavens that does not fail, where no thief approaches and no moth destroys. For where your treasure is there will your heart be also(Lk 12:32-34).
To live already now in the Kingdom of God is to live in freedom from sin and death in the gracious life of Christ and the Church. A person who has died to sin with Christ in baptism and has been sealed with the gift of the Holy Spirit in chrismation and who participates in Christ’s Body and Blood in the eucharist is already a member of the Kingdom of God.
... for through Christ we have access in one Spirit to the Father. So then you are no longer strangers and sojourners, but are fellow citizens with the saints and members of the household of God, built upon the foundation of the apostles and prophets. Christ Jesus Himself being the cornerstone, in whom the whole structure is joined together and grows into a holy temple in the Lord, in whom you also are built into it for a dwelling place of God in the Spirit (Eph 2:18-22).
The Church is called the Kingdom of God on earth; and the presence and power of the Kingdom is identified with the indwelling of the Holy Spirit who abides in the faithful bringing to them the presence and power of God the Father through His Son Jesus Christ.
Thus the Apostle Paul has said, “The Kingdom of God is… righteousness and peace and joy in the Holy Spirit; he who thus serves Christ is acceptable to God and approved by men” (Rom 14:17-18). And Saint Gregory of Nyssa (4th c.) citing the earlier tradition of Christians said simply: “The Kingdom of God is the Holy Spirit. ...The Kingdom of the Father and the Unction of the Son.” It has always been understood in the spiritual tradition of the Orthodox Church that to the measure with which one is filled with the Spirit of God, to that same measure he is united with Christ and is in communion with the Father, becoming His child and a member of His Kingdom. Thus it is the teaching that the “acquisition of the Holy Spirit” in “seeking first the Kingdom of God and His righteousness” (Mt 6:33) is the sole purpose and content of man’s spiritual life. It is for this, and this alone, that man has been created by God.
...Walk by the Spirit, and do not gratify the desires of the flesh. For the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh; for these are opposed to each other. ...Now the works of the flesh are plain: immorality, impurity, licentiousness, idolatry, sorcery, enmity, strife, jealousy, anger, selfishness, dissension, party spirit, envy, murder, drunkenness, carousing, and the like. ...those who do such things shall not inherit the Kingdom of God(Gal 5:16-21).
From:The Orthodox Faith by Fr. Thomas Hopko