On Prayer 22.2

And even if God is called Father, and those begotten by the word of faith in him are called sons, the firmness and unchangeableness of sonship is not to be seen among the ancients. At any rate the very passages we have cited show that those called sons were blameworthy; since, according to the apostle, as long as “the heir is a child, he differs in nothing from a slave, though he is lord of all, but is under guardians and stewards until the time appointed by the father.” And “the fullness of time” is present in the coming of our Lord Jesus Christ, when those who wish receive adoption as sons, as Paul teaches in these words: “For you did not receive a spirit of slavery to fall back into fear, but you received the spirit of adoption, in which we cry, Abba, Father”; and in the Gospel according to John: “But to all who received him he gave power to become children of God, to those who believe in his name.” And because of this “spirit of adoption” we have learned in the catholic letter of John about those born of God that “everyone who is born of God does not commit sin, because his seed abides in him; and he cannot sin, because he has been born of God.”