Augustine talks about this in
Of Faith and Works:
“At present I am still occupied in this question, wherein it appears to them right to admonish them that are already baptized concerning the morals which pertain unto a Christian life, but in the case of them yet to be baptized to introduce faith only. Which if it were so, besides so many things which we have said, John the Baptist would not say unto persons coming unto his baptism, ‘Generation of vipers, who hath pointed out to you to flee from coming wrath? Produce therefore worthy fruits of repentance’ (Matt. 3:7-8). Which admonitions of his are surely not on the matter of faith, but of good works. Whence also unto the soldiers who said, ‘What shall we do’ (Luke 3:14), he said not, ‘In the mean time believe and be baptized, afterwards ye shall hear what ye ought to do’; but he before said, he before premonished them, that as a forerunner he might cleanse the way, for the Lord Who was to come into their hearts: ‘Do violence to no man, bring false accusation against no man, let your own pay suffice to you’ (Luke 3:14). In like manner unto the publicans who asked what they ought to do, he said, ‘Exact nothing further than what is appointed unto you’ (Luke 3:13). In briefly making mention of these things, the Evangelist (for he needed not to insert whole Catechisms) hath shewed sufficiently, that it pertaineth unto him who catechizes one about to be baptized, to teach and admonish him concerning morals. But if they had made answer to John, ‘We will not at all produce worthy fruits of repentance, we will accuse falsely, we will do violence, we will exact those things which are not owed to us’; and yet notwithstanding he were to baptize them after this profession; yet not even thus could it be said, (what is the present question,) that it is not proper to the time at which each man is to be baptized, to discourse unto him first after what manner he ought to lead a good life” (
, Ch. 13.19Of Faith and Works).
Augustine says that even if Scripture were silent on this point, we know from apostolic succession that catechesis is necessary prior to baptism:
“But if Scripture hath been silent, and hath left for us to understand the rest of what Philip did with the Eunuch about to be baptized, and, in that it saith, ‘Philip baptized him’ (Acts 8:38), hath willed that we should understand that all things were fulfilled, which although they be passed over in the Scriptures for the sake of brevity, we yet by the line of tradition know are to be fulfilled; in like manner also, in that it was written, that Philip ‘preached’ unto the Eunuch ‘the Lord Jesus’ (Acts 8:35), we are in no way to doubt that those things also were said in the teaching, which pertain unto the life and manner of him who believed in the Lord Jesus Christ” (
, Ch. 9.14Of Faith and Works).
With love in Christ,
Pete