The authority of Pope Stephen I has been alleged for the validity of baptism given in the name of Christ only. St. Cyprian says (Epistle 72) that this pontiff declared all baptism valid provided it was given in the name of Jesus Christ. It must be noted that the same explanation applies to Stephen's words as to the Scriptural texts above given. Moreover, Firmilian, in his letter to St. Cyprian, implies that Pope Stephen required an explicit mention of the Trinity in baptism, for he quotes the pontiff as declaring that the sacramental grace is conferred because a person has been baptized "with the invocation of the names of the Trinity, Father and Son and Holy Ghost".

A passage that is very difficult of explanation is found in the works of St. Ambrose (On the Holy Spirit I.3), where he declares that if a person names one of the Trinity, he names all of them: "If you say Christ, you have designated God the Father, by whom the Son was anointed, and Him Who was anointed Son, and the Holy Ghost in whom He was anointed." This passage has been generally interpreted as referring to the faith of the catechumen, but not to the baptismal form. More difficult is the explanation of the response of Pope Nicholas I to the Bulgarians (cap. civ; Labbe, VIII), in which he states that a person is not to be rebaptized who has already been baptized "in the name of the Holy Trinity or in the name of Christ only, as we read in the Acts of the Apostles (for it is one and the same thing, as St. Ambrose has explained)". As in the passage to which the pope alludes, St. Ambrose was speaking of the faith of the recipient of baptism, as we have already stated, it has been held probable that this is also the meaning that Pope Nicholas intended his words to convey (see another explanation in Pesch, Prælect. Dogm., VI, no. 389). What seems to confirm this is the same pontiff's reply to the Bulgarians (Resp. 15) on another occasion when they consulted him on a practical case. They inquired whether certain persons are to be rebaptized on whom a man, pretending to be a Greek priest, had conferred baptism? Pope Nicholas replies that the baptism is to be held valid "if they were baptized, in the name of the supreme and undivided Trinity". Here the pope does not give baptism in the name of Christ only as an alternative. Moralists raise the question of the validity of a baptism in whose administration something else had been added to the prescribed form as "and in the name of the Blessed Virgin Mary". They reply that such baptism would be invalid, if the minister intended thereby to attribute the same efficacy to the added name as to the names of the Three Divine Persons. If, however, it was done through a mistaken piety only, it would not interfere with the validity (S. Alph., n. 111).