TONSURE - The tonsure, which is the cutting of hair from the head in the sign of the cross, is the sign that the person completely offers himself to God -- hair being the symbol of strength (Jud 16:17). Thus, until the fifteenth century the clergy of the Orthodox Church -- the "professional Christians," so to speak -- wore the tonsure all their lives to show that their strength was in God.
As Christians we are called to offer our entire life to the Lord. As a symbolic first-offering, the candidate?s hair is cut. Hair, in the Biblical story of Samson is equated with strength; thus the hair offered stands for all the person's strength and potentials given over to God.