The Mystery of Priesthood"
The sacrament of Priesthood (holy orders) is not obligatory for every Christian. Not all are capable of becoming clergy—only those who sincerely desire to dedicate their entire lives to serving God and the Church, and who are worthy of the sacred ministry.
The Lord Jesus Christ Himself chose special ministers for His Holy Church. He gave the apostles the authority to teach and to perform the sacraments:
“Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost” (Matthew 28:19).
“Whose soever sins ye remit, they are remitted unto them; and whose soever sins ye retain, they are retained” (John 20:23).
After Christ’s ascension into heaven, the Holy Ghost was sent down, endowing the apostles with the power needed for ministry. This power is transmitted from generation to generation, from one clergyman to another, through the laying on of hands.
The sacrament of holy orders is accompanied by the laying on of the bishop’s hands upon the head of the one being ordained — this is called ordination. Ordination is the exclusive authority of a bishop; no other clergyman can perform it. A bishop ordains church ministers — candle-bearers and readers (through khirothesia) — and sacred ministers — deacons, priests, and fellow bishops (through khirotonia). Each rank of ordination has its own particular rites, and each rank serves a distinct function.
The ordination of bishops, presbyters (priests), and deacons is performed during the Divine Liturgy, though at different points within it. Ordination to the diaconate takes place after the consecration of the Holy Gifts, since a deacon serves at the sacraments but does not have the authority to perform them. Ordination to the priesthood occurs after the Great Entrance, so that the newly ordained may immediately take part in the Eucharistic celebration. Ordination to the episcopate is performed at the beginning of the Liturgy, because the bishop has the authority not only to celebrate the sacraments, but also to ordain others into holy orders. Moreover, episcopal ordination is performed by a synod of bishops (at least two), whereas ordination to the presbyterate and diaconate may be done by a single bishop.