Thomas Aquinas (1225–1274) was a Dominican friar and one of the greatest philosophers and theologians of Western history. His works include the Summa Theologica (Summary of Theology), Summa Contra Gentiles, and Compendium of Theology. The Protestant Reformers critiqued Aquinas while appreciating and utilizing his work. This article summarizes some of the reasons that Aquinas gives for why God became incarnate.
1. God became man to free human nature from sin so that we could be perfectly happy. God created us for perfect happiness; however, human nature became corrupted by sin, which prevents our happiness in God (see Questions 1 and 2 of the catechism). Aquinas explains, “Human nature was unable to arrive at perfect happiness except with such corruption being removed” (CT 199). It would have been inappropriate for God to create man for a purpose, only for all of humanity to fail to reach that goal. “Inasmach as human beings have been made for the sake of happiness, since happiness is their final end, God’s work in so excellent a creature would then have been in vain” (CT 199). Therefore, it was necessary for God to become man to restore human nature so that humanity could be happy in God.
2. God became man because only a God-man was able to both restore human nature and satisfy divine justice against sin. In the beginning, God created man righteous by a gift of his free grace. After he sinned, Adam could not return to his former innocence by any work or merit of his own. Only God could restore man (CT 198). However, if God had done this by a simple act of will and power—simply “snapping his fingers” to save humanity—then “the order of divine justice” would not have been satisfied against sin. At the same time, it was necessary that the satisfaction for sins be made by humanity, since humanity is subject to God, and not the other way around. Yet no mere human being was able to do so. The incarnation answers this dilemma: “It was appropriate that God became a human being, so that the one who was able to repair human nature and the one who was able to make satisfaction for sin would be one and the same” (CT 200). “A mere man could not have made repayment for the whole human race, but God was not bound to repay; therefore, it was proper for Jesus Christ to be both God and a human being” (ST 3.1.2). As man, he died for sin; as God, he conquered sin and death.
God became man because only a God-man was able to both restore human nature and satisfy divine justice against sin.
It’s important to note that when Aquinas speaks of the “necessity” of the incarnation for our salvation, he does not mean that we could not have been saved without it (although other theologians take this view). Aquinas thinks that God could have restored human nature in “many other ways,” as did Augustine before him (On the Trinity 13.10). When Aquinas says that the incarnation was “necessary,” he means it in a second sense of “arriving at the goal in a better and more fitting manner, in the way that a horse is necessary for a journey.”
3. God became man because in his infinite goodness he wanted man to reach his created potential for good. God created human beings with potential to become better or worse. We are not “immovably confirmed” in evil or good. Aquinas concludes that it would have been inappropriate for God, who is perfectly good, to allow human beings to remain in corruption without any possibility of becoming good as he is good. “It was not appropriate for divine goodness to have left this potentiality completely empty, which would have been the case if God were not to have procured a remedy to restore it” (CT 199). The incarnation furthers us in good with regard to (1) faith, which is made more certain by hearing God speak as Truth incarnate; (2) hope, which is greatly raised up by seeing God humbly share in our nature for our good; and (3) charity or love, which is greatly stirred up by seeing God’s love for us in the incarnation.
4. God became man to show us his great love so that we would serve him out of love instead of fear. God “clearly showed the immensity of his love for human beings, so that they as a result would now be subject to God by the desire of love, not the fear of death” (CT 201). Aquinas cites Augustine On the Instruction of Beginners in asking, “What greater cause is there of the Lord’s coming than to show God’s love for us?” (ST 3.1.2).
5. God became man to give us a perfect human example to follow. God furthers us in good with regard to right action by providing us Christ as an example. “So that we might be shown one who could be both seen and followed by human beings, God was made a human being” (ST 3.1.2).
6. God became man to draw man away from material things and recall us to divine things. When humanity fell, we became immersed in material things instead of God. By coming among us, God recalled us to spiritual things “by the mystery of his body” (CT 201).
7. God became man to demonstrate the dignity of human nature so that we would no longer subject our nature to sin or Satan, which are unworthy of us. God created human beings for excellence and for union with himself. Instead, we human beings use our bodies for immoral and inappropriate things. By becoming incarnate, God clearly demonstrated how much we are worth to him so that we would no longer subject ourselves to demons or to material things (CT 201). The incarnation teaches us not to stain our nature by sin or to honor Satan, the author of sin, by allowing him to gain control over us (ST 3.1.2). Augustine quotes Pope Leo’s Sermon 21, “O Christian, acknowledge your worth and, having been made a partner of the divine nature, refuse to return to your former worthlessness through evil deeds.”
8. God became man so that man could become god—that is, share in the divine nature insofar as it is possible for human nature. Aquinas attributes to Augustine the well-known saying, “God became a human being, that human beings might become God.” Aquinas and the fathers are clear that human beings cannot become God in the sense of crossing the Creator-creature divide. When they say that man becomes “god,” they mean “divine,” “God-like,” or “godly.” It is a provocative way of leaning into the language of 2 Peter 1:4, which says that we are made “partakers of the divine nature.” This is commonly called divinization or theosis, and Aquinas emphasizes that it is “true human blessedness and the goal of human life” (ST 3.1.2). By uniting the divine and human natures in the hypostatic union, Christ made it possible for human beings to share more fully in God’s communicable attributes.
By uniting the divine and human natures in the hypostatic union, Christ made it possible for human beings to share more fully in God’s communicable attributes.
9. God became man to give us confidence about the possibility of the beatific vision—man seeing God. It has already been noted that God created man for perfect happiness, and that this happiness requires man to be united with God and so share in God’s divine nature. Aquinas also explains that this perfect happiness will be ultimately realized when man, having partaken in the divine nature, sees the essence of God—not with his eyes, but with his intellect. This is commonly called the beatific vision. It is difficult for us, however, to believe that our created mind could ever enjoy such union with the infinite and uncreated God. Therefore, God joined the divine and human natures in the hypostatic union to give us “an example of the blessed union by which the created intellect will be united to the uncreated spirit by understanding. For it does not remain unbelievable that a created intellect can be united to God by seeing his essence, since God has been united to a human being by assuming the nature of a human being” (CT 201).
10. God became man as an act of incredible grace and humility to strip us of all pride and self-righteousness. The incarnation takes away all human presumption. Human beings did nothing to deserve or merit God coming among us in Christ. The pure gift of the incarnation shows us that salvation is not of any merit of our own. Aquinas quotes Augustine On the Trinity 13.17, “The grace of God is shown to us in the man Christ, though no merits went before” (ST 3.1.2). Likewise, the incarnation takes away all human pride. Aquinas quotes the same passage from Augustine: “Human pride, which is the greatest stumblingblock to our clinging to God, can be refuted and cured by such humility on the part of God” (ST 3.1.2).
Human beings did nothing to deserve or merit God coming among us in Christ.
11. God became man to draw human beings back to himself who is our created source. “The universe of God’s whole work of creation is in a way perfected when human beings, who were created last, return cyclically to their source, united by the work of the incarnation to the very source of things” (CT 201).
12. God became man so that by visible things his invisible nature would be more fully revealed. “It would seem to be most fitting that the invisible things of God should be made known by visible things, since it was for this purpose that the whole world was made” (ST 3.1.1; cf. Rom. 1:20). Aquinas cites John of Damascus On the Orthodox Faith, who explained that the mystery of the incarnation reveals (1) God’s goodness, since God did not despise the weakness of humanity, which was his own handiwork; (2) God’s justice, since God “did not snatch humanity forcibly from death, but caused the tyrant to be defeated by no other”; (3) God’s wisdom, since “he found a suitable solution for a most difficult problem”; and (4) God’s infinite power or virtue, since “nothing is greater than for God to become a human being” (ST 3.1.1).
13. God became man for many other reasons which are beyond the perception of human comprehension. Aquinas emphasizes that the incarnation is a mystery so great that we can never fully grasp it. As Christians, we should never grow tired of meditating on the meaning of the incarnation, year after year, and exploring the wealth of the Church’s resources that address the question, “Why did God become man?”
