The idea of the priesthood follows, as we have said, the conception of the liturgical sacrifice. The word ‘sacrifice’ (θυσια) first occurs in this connection I the Didache. But something similar is meant when the first epistle of Clement (44.4)—in the last decade of the first century—speaks of an ‘offering of the gifts’, which the bishops perform for the communities during the service. With this in view it is perfectly understandable that these Christian bishops should very soon be seen as closely parallel with the priests of the Old Covenant, and this, in the opinion of the writer of the epistle should firmly secure their permanent rights in the execution of the cult. The word ‘sacerdos’, priest, first appears as applied to the Chrisitan bishops and presbyters in Tertullian. Evidently, he alludes, not so much to the idea of a special priestly dignity according to the clergy, as to the distinct function the priest has to exercise in virtue of his office. (Hans von Campenhausen, “The Origins of the Idea of the Priesthood in the Early Church,” in Tradition and Life in the Early Church: Essays and Lectures on Church History [London: St James’s Place, 1968], 220)
The essential dependence of the priest on the Church and the community as a whole is further shown—this is our second point—in the ever-present possibly of his forfeiting his sacerdotal office and power, if he should leave the community of the true Church. In such a case, he could no longer ordain, even if he was a consecrated bishop, nor even, according to Cyprian, baptize; and the Council of Nicaea expressly laid down that any schismatical priest entering the ranks of the Catholic clergy was to be ordained anew. In fact, the Council of Chalcedon (sixth century), declared null (ακυρος χειροντονια) even a Catholic ordination as a priest of someone perfectly orthodox is performed without reference to a definite community, null, therefore, as an ‘absolute ordination’. In other words, it is not merely, as most Catholic scholars make out, illegal, but absolutely ineffective and meaningless, and the person receiving such ordination remains a layman. Behind the priest must stand the Church, the community of God, which sustains him and his service in the same Holy Spirit as that with which he, in his priestly capacity, represents it before God. Apart from this community, any supposed priesthood any consecration and ordination, mean in fact nothing. (Hans von Campenhausen, “The Origins of the Idea of the Priesthood in the Early Church,” in Tradition and Life in the Early Church: Essays and Lectures on Church History [London: St James’s Place, 1968], 222)
