Augustine, commenting on 1 Tim. 1.15, gives what he believes is the cause of Christ’s Incarnation. Just as we saw in the cases of B.B. Warfield and Irenaeus, here too the cause is human sin; that is, the Incarnation is soteriologically motivated.
1. 1. Quod lectum est modo de sancto Evangelio, hoc et Paulus apostolus dicit, cuius verba ista sunt: Fidelis sermo et omni acceptione dignus, quia Christus Iesus venit in mundum peccatores salvos facere, quorum primus ego sum . Nulla causa fuit veniendi Christo Domino, nisi peccatores salvos facere. Tolle morbos, tolle vulnera, et nulla causa est medicinae. Si venit de caelo magnus medicus, magnus per totum orbem terrae iacebat aegrotus. Ipse aegrotus genus humanum est.
That which was read just now from the holy Gospel, this Paul the Apostle also says, whose words are as follows: “It is a saying faithful and worthy of all acceptance, that Christ Jesus came into the world to save sinners, of whom I am the foremost.” For Christ the Lord had no reason for coming, except to save sinners. Take away diseases, take away wounds, and there is no reason for medicine. If the great physician came from heaven, great was the sick man languishing over the whole earth. The human race is that sick man. (Sermon 175.1)1