2 In the Gospel according to the Hebrews, which is written in the Chaldee and Syrian language, but in Hebrew characters, and is used by the Nazarenes to this day (I mean the Gospel according to the Apostles, or, as is generally maintained, the Gospel according to Matthew, a copy of which is in the library at Cæsarea), we find, “Behold, the mother of our Lord and His brethren said to Him, John Baptist baptizes for the remission of sins; let us go and be baptized by him.
But He said to them, what sin have I committed that I should go and be baptized by him? Unless, haply, the very words which I have said are only ignorance.” And in the same volume, “If your brother sin against you in word, and make amends to you, receive him seven times in a day.” Simon, His disciple, said to Him, “Seven times in a day?” The Lord answered and said to him, “I say unto you until seventy times seven.” Even the prophets, after they were anointed with the Holy Spirit, were guilty of sinful words.
Ignatius, an apostolic man and a martyr, boldly writes, “The Lord chose Apostles who were sinners above all men.” It is of their speedy conversion that the Psalmist sings, “Their infirmities were multiplied; afterwards they made haste.” If you do not allow the authority of this evidence, at least admit its antiquity, and see what has been the opinion of all good churchmen. Suppose a person who has been baptized to have been carried off by death either immediately, or on the very day of his baptism, and I will generously concede that he neither thought nor said anything whereby, through error and ignorance, he fell into sin.
Does it follow that he will, therefore, be without sin, because he appears not to have overcome, but to have avoided sin? Is not the true reason rather that by the mercy of God he was released from the prison of sins and departed to the Lord? We also say this, that God can do what He wills; and that man of himself and by his own will cannot, as you maintain, be without sin. If he can, it is idle for you now to add the word grace, for, with such a power, he has no need of it. If, however, he cannot avoid sin without the grace of God, it is folly for you to attribute to him an ability which he does not possess. For whatever depends upon another's will, is not in the power of him whose ability you assert, but of him whose aid is clearly indispensable.
Source: Against the Pelagians (New Advent)