Can Christians use Philosophy to Understand Theology?

The early Church father Tertullian famously asked, “What has Athens to do with Jerusalem?” This was a question of the relationship between the Christian faith and Greek philosophy. Should we bring philosophical categories and concepts to bear on our study of God? Does human reason have a place in our theology? 

Let us travel back to the 13th century and examine the writing of Thomas Aquinas, who is widely considered one of the greatest teachers in church history. I encourage you to follow along as I explore Aquinas’ thought on the relationship between human reason and the Christian faith. Aquinas synthesizes the teachings of many earlier Christians, and he has much wisdom to offer on the relationship between philosophy and faith.

Aquinas usually writes in a format known as disputed questions, which has the following pattern:

• He proposes a thesis or question
• He explains the strongest objections to the thesis or question
• He offers his own position and argues for it
• He responds to all of the above objections

This format follows a consistent structure that readers can follow. It also shows his desire to articulate his opponent’s arguments before ever offering his own. He builds a steel-man instead of a straw-man. He values intellectual honesty. With this structure in mind, let us examine Aquinas’ writing on this topic.¹ 

This position begins with the premise that Scripture is the highest authority for Christian beliefs and practices. Human reason poses a dangerous threat to Scripture’s authority, and thus, we should be extremely wary of human reason, if not forbid it altogether. I understand this impulse, and Aquinas does too. In his steel-man of this position, he offers eight total arguments. For the sake of time, I will summarize a couple of them. 

1. The wisdom of the world is contrary to the gospel of God. Aquinas quotes 1 Corinthians 1:17, “For Christ did not send me to baptize but to preach the gospel, and not with words of eloquent wisdom, lest the cross of Christ be emptied of its power.” He also quotes Verse 20, “Where is the one who is wise? Where is the scribe? Where is the debater of this age? Has not God made foolish the wisdom of the world?”
2. Heretics often use the teachings of philosophy to distort the faith. Therefore, we ought to steer clear of these philosophical teachings. 
3. Scripture refutes the teachings of philosophy on many points, and thus philosophy cannot provide support for our faith. 

Aquinas supports his position in a few ways. Most importantly, he begins by quoting three passages where the Apostles reference Greek philosophers: Titus 1:12, 1 Corinthians 15:33, and Acts 17:28. For Aquinas, these Scriptures are enough to prove his point. Still, he goes on to offer more arguments: 

1. Numerous, church fathers, including Basil, Gregory, Jerome, Augustine, and others appealed to human reasoning in matters of faith. 
2. We can take philosophy captive, discarding the false parts and appropriating the parts that are useful and in agreement with the Christian faith. Both Jerome and Augustine commend this practice. Where human wisdom aligns with the truth, Augustine says “we must not only have no fear of them but appropriate them for our own use from those who are their unlawful possessors.”
3. It is often necessary to use good philosophy in order to correct bad philosophy. 

For these reasons, philosophy is permissible in discussions of philosophy. But what role does it play? How do we safeguard against the danger of elevating philosophy above Scripture? 

Aquinas’ has much to say about the role of reason in discussions of theology. My aim here is to condense it into four bite-sized portions for you to consider. The following theses show how we can hold human reason in high regard and use philosophy to support our faith, without compromising the authority of Scripture or our faith in Christ. 

1. Faith is not contrary to reason. Rather, faith perfects reason. Both faith and reason are God-given. God gave us a natural world with laws of logic and science, and he gave us a mind to interpret them. The human mind needs the guidance of Scripture in matters of faith. Nevertheless, what God reveals through Scripture cannot contradict what He reveals through nature, since both are from Him. Aquinas is clear that reason alone is “inadequate” and “imperfect.” The principles of philosophy “fall short” of the Christian faith. But although human reason is imperfect, it is not in contradiction to faith. The imperfect bears a shadowy resemblance of the perfect. In this way, human reason gives some knowledge of God, but Scripture lights the way where reason falls short. 
2. Reason can demonstrate certain presuppositions of the Christian faith. We can learn certain truths about God through the natural world, namely that “God exists, that He is One, and other truths of this sort about God or creatures proved in philosophy and presupposed by faith.” Scripture does not seek to prove God’s existence; it assumes it. When Paul preaches in Athens, he does not jump straight into the Gospel. He begins by asserting that God is the Creator, He is not confined to temples (i.e. Infinity), and He has no needs (i.e. Aseity). These doctrines of God are not enough. Faith in Christ is necessary for salvation. But the Christian faith presupposes certain truths about the identity of God, which the natural world can demonstrate. Romans 1:20 says, “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.” 
3. Reason can refute philosophical claims that contradict the faith. Since faith is not contrary to reason, it follows that if any philosopher makes a claim that contradicts the faith, their reasoning is faulty. They are abusing philosophy, and this abuse can be corrected through the proper use of philosophy, knowing that all truth is from God. 
4. Reason is secondary to faith in Scripture and in Christ. We should never hold reason above Scripture. In the words of Aquinas, “the teaching of the philosophers is not to be used as though it is held in first place, in such a way that the truth of faith should be believed because of it.” Human reasoning serves a supplementary role to the faith that Scripture reveals. Aquinas writes that philosophy is the handmaiden, or servant, of theology.² It can get us part way by demonstrating God’s existence and invisible attributes, but it cannot give us the knowledge that comes through faith in Jesus Christ. 

So, what has philosophy to do with theology? Human reason is supplementary. It is a servant. It should not be discarded. It cannot teach us everything we need to know about God and Christ, but it can teach us a lot.

At this point you might be thinking, “okay, I’ll grant that philosophy is permissible. It’s not forbidden. But Scripture is sufficient. We don’t need anything else for our faith.” True. The Westminster Confession plainly states that Scripture contains contains “all things necessary for His own glory, man’s salvation, faith and life.”³ Clearly, One can put their faith in Christ and receive salvation without any knowledge of philosophy. Nonetheless, philosophy carries massive importance for the Christian life because it helps correct false interpretations of Scripture. In future articles, we will explore how philosophy demonstrates crucial truths about God’s nature, and thus protects against those who would twist Scripture to paint a false view of God. Until then, let us thank God for the manifold ways that He has revealed Himself to us. Let us thank him for the gift of natural reason and the superior gift of his written Word. 

1. Unless otherwise noted, all references to Thomas Aquinas are taken from Faith, Reason and Theology, Question Two, Article Three. ↩︎
2. Thomas Aquinas, Summa Theologiae, Part One, Question One, Article Five. ↩︎
3. Westminster Confession of Faith, 1.6 ↩︎