This great work was, indeed, supremely worthy of the goodness of God. A king who has founded a city, so far from neglecting it when through the carelessness of the inhabitants it is attacked by robbers, avenges it and saves it from destruction, having regard rather to his own honor than to the people's neglect. Much more, then, the Word of the All-good Father was not unmindful of the human race that He had called to be; but rather, by the offering of His own body He abolished the death which they had incurred, and corrected their neglect by His own teaching. Thus by His own power He restored the whole nature of man.
The Savior's own inspired disciples assure us of this. We read in one place: "For the love of Christ constrains us, because we thus judge that, if One died on behalf of all, then all died, and He died for all that we should no longer live to ourselves, but to Him who died and rose again from the dead, even our Lord Jesus Christ." And again another says: "But we behold Him Who was made a little lower than the angels, even Jesus, because of the suffering of death crowned with glory and honor, that by the grace of God He should taste of death on behalf of every man."
The same writer goes on to point out why it was necessary for God the Word and none other to become Man: "For it became Him, for Whom are all things and through Whom are all things, in bringing many sons to glory, to make the Author of their salvation perfect through suffering." He means that the rescue of humanity from corruption was the proper part only of Him Who made them in the beginning.
He points out also that the Word assumed a human body, expressly in order that He might offer it in sacrifice for other like bodies: "Since then the children are sharers in flesh and blood, He also Himself assumed the same, in order that through death He might bring to nothing the one who has the power of death, that is to say, the Devil, and might rescue those who all their lives were enslaved by the fear of death."
For by the sacrifice of His own body He brought the law against us to an end and renewed for us a beginning of life, giving us the hope of resurrection. Since death gained power over human beings through a human being, the destruction of death and the resurrection of life likewise came through the Incarnation of God the Word. As the man who bore Christ says, "For since death came through a human being, the resurrection of the dead also came through a human being. For just as all die in Adam, so all will be made alive in Christ," and what follows. We no longer die as those under condemnation, but as those who are to rise, awaiting the common resurrection of all, "which in His own times He will reveal"—God, Who accomplished it and graciously gave it to us.
This, then, is the first cause of the Savior’s Incarnation. From what follows, one may also understand that His gracious coming among us took place for good reason.