PENTECOST - (Gr. fiftieth day) Originally an OT harvest festival celebrated fifty days following the Passover. In time, Pentecost became the commemoration of the giving of the Law to Moses on Mt. Sinai. Pentecost took on a new meaning with the descent of the Holy Spirit on the apostles at Pentecost. Through the Sacrament of Chrismation, Orthodox Christians experience their own personal Pentecost. Every Divine Liturgy becomes a Pentecost through the descent of the Holy Spirit on the faithful and the gifts (the bread and wine), transforming them into the Body and Blood of Christ. (Ex. 23:14-17; Lev. 23:15 21; Acts 2:1 41.)
The feast on which is commemorated the coming-down of the Holy Ghost upon the Apostles and the establishment of the Church founded by our Lord. This feast is also called Trinity Sunday. It occurs fifty days after Easter. The following day is the Feast of the Holy Ghost. The Sundays following this feast up to the third Sunday before Lent are numbered as Sundays "after Pentecost." It is the custom to decorate the church on Pentecost Day with green branches to express "new life" and "new power."