Saint Peter wrote, “You are a chosen race, a royal priesthood, a holy nation, God’s own people” (1 Pet. 2:9). It is true that all Christians share in the priesthood of Christ through Baptism, yet this common priesthood is to be distinguished from the ministerial priesthood. What Peter said to the faithful in the New Testament, in fact, was also said to Israel in the Old, “You shall be to me a kingdom of priests and a holy nation” (Ex. 19:6). Within the priestly nation of Israel, however, existed a distinct, ministerial priesthood, the Levitical priesthood. It is the same for God’s people in the New Covenant. We, too, are a priestly nation; and within our ranks exists a special, sacramental priesthood charged with presiding over the Sacrifice of the Mass, our communal act of worship.
Our view of the Mass as a sacrifice sets Catholics apart from other Christians. At Mass the sacrifice of Christ on the Cross is made sacramentally present to us on the altar through the Holy Eucharist. This does not mean Jesus dies again at Mass. Rather we are in effect transported back through time to the very moment of His death so that we might witness and participate in that saving sacrifice.
In the Gospels, the Apostles are given the authority to preside over the Eucharistic celebration. We see this in the account of Christ’s multiplication of the loaves and fish, an Eucharistic metaphor, in which the Lord commands the Apostles to feed the people (Matt. 14:16). More directly, at the Last Supper, in the midst of instituting the Eucharist, the Lord commands the Apostles, “Do this in remembrance of me” (Luke 22:19). The Apostle Paul explained he was called “to be a minister of Christ Jesus to the Gentiles in the priestly service of the gospel of God, so that the offerings of the Gentiles may be acceptable, sanctified by the Holy Spirit” (Rom. 15:16). And elsewhere he wrote, “This is how one should regard us [i.e., the Apostles], as servants of Christ and stewards of the mysteries [i.e., sacraments] of God. … For though you have countless guides in Christ, you do not have many fathers. For I became your father in Christ Jesus through the gospel” (1 Cor. 4:15).
While the term “priest” may not have been widely used by Christians in apostolic times, likely to set their ministers apart from the priests of Israel (cf. Rom. 15:16, above), there is extensive evidence from the end of the first century forward of the term being applied to those who preside over the Eucharist. Writing in about the year 96 A.D., for example, Pope Saint Clement clearly distinguished between the ministerial priesthood and the priesthood of the laity. “The high priest,” he wrote, referring to Christ, “is given his duties: the priests [i.e., bishops] are assigned their special place, while on the Levites [i.e., deacons] particular tasks are imposed. The layman is bound by the layman’s code” (Letter of Clement to the Corinthians 40:1-5). As a matter of fact, this is the earliest recorded instance of the term “layman.”
In about the year 107, Saint Ignatius, the Bishop of Antioch and a disciple of the Apostle John, wrote, “Good, too, are the priests; but the high priest [i.e., Christ] is better, to whom was entrusted the holy of holies; and to him alone were entrusted the secret things of God” (Letter to the Philadelphians 9:1). He also counseled Christians to “follow the bishop as Jesus Christ did the Father. Follow, too, the presbytery as you would the apostles; and respect the deacons as you would God’s law. Nobody must do anything that has to do with the Church without the bishop’s approval. You should regard that Eucharist as valid which is celebrated either by the bishop or by someone he authorizes [i.e., a presbyter]. Where the bishop is present, there let the congregation gather, just as where Jesus Christ is, there is the Catholic Church” (Letter to the Smyrneans 8).