If God is who as he is revealed in Scripture, was it really necessary for the Word of God to become incarnate to save humanity? This question is an honest one, seeing that Christians confess that God is all powerful and perfect, he could, conceivably, have restored human nature without becoming incarnate. However, Aquinas argues that according to Scripture, the mystery of the Incarnation was necessary to save humanity. To defend this Aquinas first qualifies what is meant by necessary, and then shows the benefits of Christ’s Incarnation for humanity in terms of how it helps those who believe in Christ grow in the good and withdraw from evil.
Aquinas distinguishes between two types of necessity: essential necessity and convenient necessity. The first, he argues is like the necessity of food for life. The second, is like the necessity of a horse for a long trip. “When the end is attained better and more conveniently” (III.Q1.A2). He argues that the incarnation was necessary in the second way, and not the first, because God who is all powerful could have done it differently. Yet, in light of humanity’s plight and God’s goodness, Aquinas, pointing to Augustine who says, “There was not a more fitting way of healing our misery” (III.Q1.A2).
To explain how the incarnation of the word is the most fitting way he divides his topic into two sections: How the incarnate Word draws us to the good and withdraws us from evil. Under the first section he shows how the Incarnate Word is the cause of Faith, Hope, Charity, good works and glory in the Christian. It is appropriate that Aquinas frames his understanding of Christ’s person and work in these terms, because he has just covered this path of life in Christ in the previous volume in terms of faith, hope, love, virtue, all of which leads to the end goal of “Full participation of the Divinity.” In presenting these five steps, he quotes Augustine. Let’s consider them one by one.
Christ’s incarnation furthers faith because Christ is the Truth revealed in human flesh. As Augustine says it: “In order that man might journey more trustfully toward the truth, the Truth itself, the Son of God, having assumed human nature, established and founded the faith.” Faith is established in the Truth by means of the Truth himself becoming human and revealing himself in the humility of human life. Hope is encouraged and strengthened by the revelation of God’s love for us which is most beautifully expressed in the Son of God becoming human. This same infinite divine love enkindles charity in us, according to Aquinas and Augustine, because what presents God’s love for us more than him becoming one of us and dying for us?
Having grounded Faith, Hope, and Love in the person and work of Christ, Aquinas focuses in on how Christ is our example for the perfect human life. Again, turning to Augustine, he argues that Christ makes visible the invisible God so that man could follow God’s will. For Aquinas, this is not mere imitation, but a life infused with Grace, through the Holy Spirit’s presence. (see further 1-2.Q109-114).
Faith, hope and love grounded in Christ, infused with the good works of Christ given through the Holy Spirit is the life of the Christian which leads the Christian on to end goal for which they were created: “Full participation of the Divinity, which is the true bliss of man and the end of human life; and this is bestowed upon us by Christ’s humanity; for Augustine says in a sermon: God was made man, that man might be made God.” In Christ is the whole means and ends of true human life given to all those who believe in him as John 3:16 says. It is worth nothing that Aquinas he uses the same framework of Faith, Hope and Love when he presents the reasons for Christ’s resurrection and ascension (III.Q53.a1, Q57.a2.ad3).
But the human condition is not one of neutrality, it is one of enslavement to evil. This Christ also had to free humanity form the enslavement and destitution of their fallen selves. Aquinas, explains this withdrawal from evil in five moves.
The first two moves relates to how humanity understand itself. First Christ incarnation shows us to not prefer evil and the devil over humanity itself. In other words, if God became human, then there is a certain goodness to humanity over and against the powers of evil. This is amplified by the his second point: “we are thereby taught how great is man’s dignity…” (III.Q1.A2). This has two effects in one’s Christian life, it reminds us of our God-given worth, and it exhorts us to pursue holiness.
In these first two the dignity of humanity is established, despite sin. In the third and four, Humanity is shown in Christ’s incarnation that they could not save themselves from the pride and presumption of sin. Here we see a kind of pendulum swing from one extreme to another: we either think of humanity as nothing, or as everything. Christ in his glorious humility both raises humanity up to its proper dignity, and gives humanity its properly creaturely humility. As Augustine says, quoted by Aquinas: “Because man’s pride, which is the greatest stumbling block to our clinging to God, can be convinced and cured by humility…” (III.Q1.A2).
The establishing of humanity’s proper dignity and relation to God occurs in Christ’s death, Resurrection, and Ascension, when he frees humanity from the “thraldom of sin.” Jesus, as God and man made satisfaction for humanity’s sin and death in his death and resurrection. Aquinas establishes this point by quoting Pope Leo at length:
“Weakness is assumed by strength, lowliness by majesty, mortality by eternity, in order that one and the same mediator of God and men might die in one and rise in the other – for this was our fitting remedy. Unless he was God, he would not have brought a remedy; and unless he was man, he would not have set an example.” (III.Q1.A2).
Aquinas, ends his answer by pointing his readers back to the fact that the Incarnation and ensuing saving work of the Trinity is beyond our apprehension, by positing that there are many more advantages of the incarnation given to humanity which are beyond our understanding. This is an essential reminder for Christians and Theologians, we may apprehend much about Christ and his gospel, but we will always be standing in the face of the infinite personal mystery of the Triune God and his infinite holy love.
This summary of Aquinas’s understanding of the good and necessary fittingness of the Incarnation is just a tiny taste of the deep theological and exegetical reasoning Aquinas offers in his Doctrine of Christ. I just finished reading through the 59 questions on Christ and cannot recommend them enough.