Faustus objects to the incarnation of God on the ground that the evangelists are at variance with each other, and that incarnation is unsuitable to deity. Augustin attempts to remove the critical and theological difficulties.
1. Faustus said: Do I believe in the incarnation? For my part, this is the very thing I long tried to persuade myself of, that God was born; but the discrepancy in the genealogies of Luke and Matthew stumbled me, as I knew not which to follow. For I thought it might happen that, from not being omniscient, I might take the true for false, and the false for true. So, in despair of settling this dispute, I betook myself to Mark and John, two authorities still, and evangelists as much as the others. I approved with good reason of the beginning of Mark and John, for they have nothing of David, orMary, or Joseph. John says, "In the beginning was the Word, and the Word was with God, and the Word was God," meaning Christ. Mark says, "The gospel of Jesus Christ, the Son of God," as if correcting Matthew, who calls him the Son of David. Perhaps, however, the Jesus of Matthew is a different person from the Jesus of Mark. This is my reason for not believing in the birth of Christ.
Remove this difficulty, if you can, by harmonizing the accounts, and I am ready to yield. In any case, however, it is hardly consistent to believe that God, the God of Christians, was born from the womb.
2. Augustin replied: Had you read the Gospel with care, and inquired into those places where you found opposition, instead of rashly condemning them, you would have seen that the recognition of the authority of the evangelists by so many learned men all over the world, in spite of this most obvious discrepancy, proves that there is more in it than appears at first sight. Any one can see, as well as you, that the ancestors of Christ in Matthew and Luke are different; while Joseph appears in both, at the end in Matthew and at the beginning in Luke. Joseph, it is plain, might be called the father of Christ, on account of his being in a certain sense the husband of the mother of Christ; and so his name, as the male representative, appears at the beginning or end of the genealogies. Any one can see as well as you that Joseph has one father in Matthew and another in Luke, and so with the grandfather and with all the rest up to David. Did all the able and learned men, not many Latin writers certainly, but innumerable Greek, who have examined most attentively the sacred Scriptures, overlook this manifest difference? Of course they saw it. No one can help seeing it. But with a due regard to the high authority of Scripture, they believed that there was something here which would be given to those that ask, and denied to those that snarl; would be found by those that seek, and taken away from those that criticise; would be open to those that knock, and shut against those that contradict. They asked, sought, and knocked; they received, found, and entered in.
3. The whole question is how Joseph had two fathers. Supposing this possible, both genealogies may be correct. With two fathers, why not two grandfathers, and two great-grandfathers, and so on, up to David, who was the father both of Solomon, who is mentioned in Matthew's list, and of Nathan, who occurs in Luke? This is the difficulty with many people who think it impossible that two men should have one and the same son, forgetting the very obvious fact that a man may be called the son of the person who adopted him as well as of the person who begot him.
Adoption, we know, was familiar to the ancients; for even women adopted the children of other women, as Sarah adopted Ishmael, and Leah her handmaid's son, and Pharaoh's daughter Moses. Jacob, too, adopted his grandsons, the children of Joseph. Moreover, the word adoption is of great importance in the system of our faith, as is seen from the apostolic writings. For the Apostle Paul, speaking of the advantages of the Jews, says: "Whose are the adoption, and the glory, and the covenants, and the giving of the law whose are the fathers, and of whom, according to the flesh, Christ came, who is over all, God blessed for ever."(1) And again: "We ourselves also groan within ourselves, waiting for the adoption of the sons of God, even the redemption of the body."(2) Again, elsewhere: "But in the fullness of time, God sent His Son, made of a woman, made under the law, that we might receive the adoption of sons."(3) These passages show clearly that adoption is a significant symbol. God has an only Son, whom He begot from His own substance, of whom it is said, "Being in the form of God, He thought it not robbery to be equal to God."(4) Us He begot not of His own substance, for we belong to the creation which is not begotten, but made; but that He might make us the brothers of Christ, He adopted us. That act, then, by which God, when we were not born of Him, but created and formed, begot us by His word and grace, is called adoption. So John says, "He gave them power to become the sons of God."(5)
Since, therefore; the practice of adoption is common among our fathers, and in Scripture, is there not irrational profanity in the hasty condemnation of the evangelists as false because the genealogies are different, as if both could not be true, instead of considering calmly the simple fact that frequently in human life one man may have two fathers, one of whose flesh he is born, and another of whose will he is afterwards made a son by adoption? If the second is not rightly called father, neither are we right in saying, "Our Father which art in heaven," to Him of whose substance we were not born, but of whose grace and most merciful will we were adopted, according to apostolic doctrine, and truth most sure. For one is to us God, and Lord, and Father: God, for by Him we are created, though of human parents; Lord, for we are His subjects; Father, for by His adoption we are born again. Careful students of sacred Scripture easily saw, from a little consideration, how, in the different genealogies of the two evangelists, Joseph had two fathers, and consequently two lists of ancestors. You might have seen this too, if you had not been blinded by the love of contradiction. Other things far beyond your understanding have been discovered in the careful investigation of all parts of these narratives. The familiar occurrence of one man begetting a son and another adopting him, so that one man has two fathers, you might, in spite of Manichaean error, have thought of as an explanation, if you had not been reading in a hostile spirit.
4. But why Matthew begins with Abraham and descends to Joseph, while Luke begins with Joseph and ascends, not to Abraham, but to God, who made man, and, by giving a commandment, gave him power to become, by believing, a son of God; and why Matthew records the generations at the commencement of his book, Luke after the baptism of the Saviour by John; and what is the meaning of the number of the generations in Matthew, who divides them into three sections of fourteen each, though in the whole sum there appears to be one wanting; while in Luke the number of generations recorded after the baptism amount to seventy-seven, which number the Lord Himself enjoins in connection with the forgiveness of sins, saying, "Not only seven times, but seventy-seven times;" -these things you will never understand, unless either you are taught by some Catholic of superior stamp, who has studied the sacred Scriptures, and has made all the progress possible, or you yourselves turn from your error, and in a Christian spirit ask that you may receive, seek that you may find, and knock that it may be opened to you.
5. Since, then, this double fatherhood of nature and adoption removes the difficulty arising from the discrepancy of the genealogies, there is no occasion for Faustus to leave the two evangelists and betake himself to the other two, which would be a greater affront to those he betook himself to than to those he left. For the sacred writers do not desire to be favored at the expense of their brethren. For their joy is in union, and they are one in Christ; and if one says one thing, and another another, or one in one way and another in another, still they all speak truth, and in no way contradict one another; only let the reader be reverent and humble, not in an heretical spirit seeking occasion for strife, but with a believing heart desiring edification. Now, in this opinion that the evangelists give the ancestors of different fathers, as it is quite possible for a man to have two fathers, there is nothing inconsistent with truth. So the evangelists are harmonized, and you, by Faustus's promise are bound to yield at once.
6. You may perhaps be troubled by that additional remark which he makes: "In any case, however, it is hardly consistent to believe that God, the God of Christians, was born from the womb." As if we believed that the divine nature came from the womb of a woman. Have I not just quoted the testimony of the apostle, speaking of the Jews: "Whose are the fathers, and of whom, according to the flesh, Christ came, who is God over all, blessed for ever?" Christ, therefore, our Lord and Saviour, true Son of God in His divinity, and true son of man according to the flesh, not as He is God over all was born of a woman, but in that feeble nature which He took of us, that in it He might die for us, and heal it in us: not as in the form of God, in which He thought it not robbery to be equal to God, was He born of a woman, but in the form of a servant, in taking which He emptied Himself. He is therefore said to have emptied Himself because He took the form of a servant, not because He lost the form of God. For in the unchangeable possession of that nature by which in the form of God He is equal to the Father, He took our changeable nature, by which He might be born of a virgin. You, while you protest against putting the flesh of Christ in a virgin's womb, place the very divinity of God in the womb not only of human beings, but of dogs and swine. You refuse to believe that the flesh of Christ was conceived in the Virgin's womb, in which God was not found nor even changed; while you assert that in all men and beasts, in the seed of male and in the womb of female, in all conceptions on land or in water, an actual part of God and the divine nature is continually bound, and shut up, and contaminated, never to be wholly set free.(6)