For generations evangelicals have been told to steer clear of Thomas Aquinas because he supposedly was the principal progenitor of the false teaching of salvation by works that permeates Catholicism. Since Luther rightly told us that all of Christian doctrine stands or falls with the proper interpretation of justification, and Aquinas led the Catholic Church to embrace precisely the opposite of true justification, the discerning evangelical should renounce Thomas and all his works.

Along the way, it has also been suggested to evangelicals that because Thomas taught works and a theory of sacraments that stressed outward reception without the necessity of inward faith, his version of faith was wholly alien to evangelical faith. He had no recognition—-it is alleged—-of the necessity of personal relationship with Jesus Christ. And, some speculate, he could not have had a personal relationship with the triune God at all.

Evangelicals have been wrong on both scores. Thomas did not teach salvation by works. And he knew all about interior faith and having a personal relationship with Christ—-even if he did not practice them in precisely the ways modern evangelicals do.

Luther and Justification

Let me first explain Thomas’s view of justification (how we are accepted by God in the process of salvation). For it is at this point that he ran afoul, three centuries later, of Martin Luther and the Reformation. For Thomas, God in justification makes a difference in people (which, by the way, is what Athanasius and Augustine also taught). Justification is not just the beginning of the Christian life (as Luther described it most often) but its continuation and ultimate perfection.

It is a change of inner nature, not just legal status (from being an enemy of God to becoming a friend of God). For Thomas, there is no distinction—-as there is for Luther—-between justification (God’s declaration that he accepts us) and sanctification (our inner renewal).

So there are differences on justification and salvation between Thomas and Luther on justification. But we shouldn’t exaggerate the differences. Like Luther (and Calvin, for that matter), Thomas believed justification is a gift of God procured by Jesus’ life and death and resurrection, not a reward for human accomplishment. People can do nothing on their own to guarantee it or prepare for it:

[W]hatever preparation [for saving faith] there might be in us derives from the assistance of God moving the soul towards the good. In this sense, that good movement of free choice itself, by which someone prepares to receive the gift of grace, is the action of a free choice moved by God.

Thomas insisted that no one ever “merits the first grace,” which means no one ever deserves to have God come the first time with the grace that causes the heart and mind to begin their journey back to him. Thomas talks about “merit” in the Christian life, but it is merit given to believers only because of the grace of Christ in working in them to produce righteous works. So there is a principle of grace that runs through even Thomas’s discussion of merit. Another point of similarity between Thomas and Luther, who are often presented as being violently opposed, is that Luther also saw justification as having an inner effect. Readers who want to read more on this should see my article on Thomas, Luther, and Edwards on justification.

If Thomas did not teach salvation by works, neither did he support mechanical sacraments without deep piety. In his personal spiritual life Thomas exhibited a spirituality that would put many evangelicals to shame. On a regular basis while writing his theological treatises Thomas knelt down to pray as he faced an intellectual problem, asking for divine illumination to guide his thoughts. He wrote beautiful hymns and prayers to Jesus and the Father for use in daily life and at Holy Communion. Just before the end of his life, while celebrating Mass, he fell into a trance. From that moment, and without explanation, he stopped writing and spoke little. According to his secretary, persistent questioning drew the reply that in comparison to what God had now revealed to him, all he had written seemed like chaff. An evangelical who is dazzled by God’s beauty could not have said it better.

Why Evangelicals Should Read Thomas

At this point, some evangelicals will say, so what if Thomas taught salvation by grace and had a personal relationship with Jesus? We can read him. But should we? Why read him instead of the great Protestant theologians such as Luther or Calvin or Edwards?

The answer, I propose, is that Thomas had particular brilliance on many issues of great concern to evangelicals. And because of his depth and vision, he saw some of these issues in ways that will be of immense help to us both spiritually and intellectually in our pilgrimages toward the heavenly city.

I will speak first of his beautiful mind, and then of two issues on which he can help evangelicals.

Thomas had a phenomenal mind. G. K. Chesterton reports that when Thomas was asked for what he thanked God most, he answered simply, “I have understood every page I ever read.” Often he would dictate to more than one secretary at the same time, on different subjects. One tradition insists he composed in his sleep, which probably means he composed in such deep concentration that it resembled a trance. This had occasionally unsociable effects. In 1269, at a meal with King Louis IX of France, Thomas was thinking about the false teaching of the Manichees. Although he was in the midst of guests chattering with the king, Thomas suddenly struck the table and exclaimed, “That settles the Manichees!” He called out for his secretary to come over and take dictation. As soon as he completed the dictation, he turned to the king and profusely apologized: “I am so sorry, I thought I was at my desk.”

Thomas was made “Doctor” (teacher) of the Catholic Church in 1567, and commended for study by Pope Leo XIII in 1879. The church knew he was not as eloquent as Augustine, the former professor of rhetoric, but its leaders prized his extraordinary clarity. His greatest works are his Summa Theologica (a systematic presentation of Christian doctrine using Scripture, tradition, philosophy and theology) and Summa Contra Gentiles, an apologetic work he intended to be used by missionaries to Muslims.

How He Can Help

Now for two issues on which he can help evangelicals: The first is the relation between faith and reason. About this relationship he wrote both sophisticated works accessible only to philosophers and theologians, and also popular works such as the Summa Contra Gentiles that can be understood by non-scholars as well. On this subject he drew an important distinction that has guided Christian thinkers ever since—-the difference between what we can know by reason about God and what can be known about God only by revelation in the Bible. He said we can know about God from reason alone ideas such as the following—-that God exists, that God is perfect, that God is good, and that God is changeless and everywhere and eternal and one. He argued this was some of what Paul meant when he said of all human beings:

What can be known about God is plain to them, because God has shown it to them. For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse. For although they knew God, they did not honor him as God or give thanks to him (Rom 1:19-21a).

Thomas is famous for his Five Ways or proofs of the existence of God. They argue, first, that there must be something that causes change or motion in things without itself being changed or moved by anything. Then he says that causes arranged in a series (A caused B which in turn caused C) must have a first member: “We never observe, nor ever could, something causing itself, for this would mean it preceded itself, and this is not possible.” Finally, he turns to things with varying degrees of perfection, and argues that perfections in things imply a source of perfections. The movement toward goals by things that lack intelligence (such as animals seeking food and planets pursuing perfect orbits) suggests they are governed by something intelligent.

Thomas’s Five Ways are often misunderstood. Some have ridiculed Thomas for thinking they prove the Christian God. But while Thomas said they prove what “everyone understands to be God,” he makes clear they are meant only to show a First Cause, not the Christian God per se. The Five Ways themselves are only meant to “get the ball rolling, not to bring the [proofs] to an end.”

They are the beginning of a long argument that stretches out over 35 more double-columned pages (Questions 2-11) in the Dominican Fathers edition of his Summa Theologica. It is also frequently assumed that Thomas believed these proofs would convince any unbeliever of God’s existence. But Thomas knew that sin prevents unbelievers from thinking objectively, and wrote these brief summaries more to confirm the faith of theological students than to convince village skeptics. Thomas also made it clear that reason cannot show the distinctively Christian truths about God—-such as his being triune and Savior through Christ. These truths, he said, can be known only by revelation in Scripture.

A second issue on which Thomas can shed much light is what is called natural law. This was his idea that reason can tell us certain moral absolutes that are true for all times and places. This idea has a long history going back to Aristotle, Cicero, and Augustine. But Thomas developed it with his customary precision, so that it has had a major effect ever since.

Some examples of what Thomas thought reason can show all human beings by natural law are as follows:

  1. The first command of law, ‘that good is to be sought and done, evil to be avoided.’
  2. That, generally considered, it is a good thing to preserve ourselves.
  3. Therefore procreation and the education of the young are goods.
  4. Human beings should learn what can be learned about the meaning of reality (for him this meant God) and living in society—-namely, that people should shun ignorance, not offend others needlessly, and live in civility with others.

Thomas did not mean for natural law to be a list of detailed instructions or rules for every situation. Instead it was meant to be a framework supplemented by sound practical thinking, conscience, and civil law intended to promote the common good and geared for a particular society. When civil laws agree with natural law, they could be said to participate in God’s eternal law. But when they violate natural law, they are “unjust.” They “are acts of violence rather than laws,” and “such laws do not bind in conscience.” The implication is, as Martin Luther King famously observed in his “Letter from Birmingham Jail,” that the Christian is free or perhaps even obligated to engage in civil disobedience. You can see why Aquinas’s articulation of natural law has been appreciated not only by legal theorists and moral theologians but also by human rights activists to this day.

There are many, many other ways in which a deep reading of Aquinas can be of immense help to evangelicals. He speaks with strange depth and insight to current questions of how to talk about God, what we can and cannot know about God, what virtues are peculiarly Christian and which are not, what it means to be holy and happy, the meaning of the Incarnation, and much, much more.

My concluding word to evangelicals, then, is, Do not fear! Dive into the deep waters of thought coming from one of the great minds and hearts of the Great Tradition.

For another perspective on Aquinas, read “Aquinas: A Shaky Foundation” by K. Scott Oliphint.