Athanasius of Alexandria

But this is God’s kindness to humanity, that of whom he is the maker, of them according to grace he afterwards becomes Father also. He becomes, that is, when people, his creatures, receive him into their hearts, as the apostle says, “the spirit of his Son, crying, ‘Abba, Father.’ ” And these are they who, having received the word, gained power from him to become sons of God; for they could not become sons, being by nature creatures, otherwise than by receiving the spirit of the natural and true Son. Wherefore, that this might be, “the word became flesh,” that he might make humans capable of godhood. This same meaning may be gained from the prophet Malachi, who says, “Has not one God created us? Have we not all one Father?” For first he puts “created” next to “Father” to show, as the other writers, that from the beginning we were creatures by nature. And God is our Creator through the word, but afterwards we were made sons, and thenceforward God the Creator becomes our Father also.