Anselm and Tertullian on Christianity and Philosophy

“What indeed has Athens to do with Jerusalem?”[1] Tertullian, a church father and apologist who lived in the late 2nd and early 3rd century AD, wrote a scathing critique of nominal Christians who fall headlong into false doctrine and heresies. By asking what Athens has to do with Jerusalem, Tertullian meant to critique Christians who compromised their theology to match pagan philosophy.

Tertullian’s critique is surprisingly relevant even though it is nearly 2000 years old. Even today, the Church suffers from Christians who try to baptize clichés from secular culture while forcing their theology into the boxes which American society prescribes. Tertullian is certainly correct in critiquing this harmful practice. Christians in modern America might ask: “What indeed has Hollywood to do with the local church?”

Tertullian did not mean to critique philosophy in general, however. Tertullian was a highly educated Roman citizen—he even practiced law in ancient Rome! Once converted to Christianity, Tertullian did not turn his back on the fruits of his pagan education; instead, Tertullian drew on his knowledge as he defended Christianity. In his post-conversion writings, Tertullian used his understanding of Roman law, philosophy, ancient literature, and world history to defend and define Christianity.[2] Read in context, Tertullian means that we fall into error whenever we adjust our theology according to the dictates of secular culture.[3]

Philosophy and theology are not enemies by any means; in fact, philosophy has traditionally been viewed as the handmaiden of theology. Mature Christians can and should use philosophy to better understand Christian doctrine and praxis. Writing at the end of the 11th century, Anselm of Canterbury said: “I do not think that anyone deserves to be rebuked, if, after becoming well-grounded in the faith, he has conceived a desire to exercise himself in the investigation of its logic.”[4] According to Anselm, Christians should seek to investigate the logic of the Christian faith; in context, Anselm is about to use logic to explain that the only way that we could be saved was through the actions of a God-man, whom we know as Jesus. Anselm gives three reasons to think that Christians should use philosophy to better understand their faith before giving a word of warning in tune with that of Tertullian.

  1. No one has fully explored the depths of Christian theology.

Anselm writes: “Even the Fathers, because ‘the days of men are short’ [cf. Job 14: 1], were not able to say all that they could have said if they had lived longer; and the logic of the truth is so copious and profound that it cannot be exhausted by mortals.”[5]

The Bible is a large book to say the very least (click here for more information on how to understand the Bible). Even though the Bible has over 31,000 verses and approximately 775,000 words, the Bible does not and cannot exhaust all of Christian theology and practice.[6] The reason is not a shortcoming of the Bible; instead, the Bible is not exhaustive for two reasons. First, according to Anselm, the reason that the Bible doesn’t contain everything about Christianity is that the authors of the Bible didn’t live long enough to write everything! Second, God apparently did not intend to tell us every single thing about Christianity in the Bible. I can easily think of numerous areas that philosophical inquiry can help Christians better understand their faith and practice.

First, the Bible does not fully explain every Christian doctrine. Take the debate between Calvinists and Arminians: Calvinists claim that God elected who would be saved before the creation of the world and that the elect are invariably saved; Arminians demur and claim that God elects to salvation those whom he foreknew would freely accept salvation. Interestingly enough, one of the driving forces in this debate is the difference between two philosophical definitions of free will. Both sides can marshal numerous proof texts from scripture to support their position; with regards to this question, it seems that the Bible is ambiguous enough for both sides to have strong arguments in support of their position while leveraging damaging arguments against their opponents. To resolve arguments like this, philosophy can be of use.

Second, the Bible does not fully explain every Christian practice. We can get hints about what preaching should be from the Bible; however, the Bible does not prescribe every practice regarding preaching. When should the sermon be located in the service? Must the preacher use the Bible? What’s the optimal number of sermon points? One’s philosophy of preaching will answer these questions.

  1. God still leads his Church.

Anselm writes: “The Lord, whose promise is to be with the Church ‘until the end of the world’ [Matt. 28: 20], does not cease to bestow his gifts within it.”[7]

This is a very simple argument: God gave godly leaders to his followers in the past to guide the Church. Some, like Paul, did it through authoritative scripture. Many others, like Thomas (one of the disciples), led the Church through preaching and never wrote a single syllable of scripture. Though the canon of scripture is closed and no more books will be added to the Bible, God still provides godly leaders to lead the Church to understand how biblical principles apply to their lives. The Bible does not directly address many concerns of the modern world such as bioethics and nuclear war; therefore, Christian leaders, whom God has given to his Church, must use philosophical principles to understand how the Bible speaks to modern questions.

  1. God orders us to think through our faith.

Anselm writes: “Where he says, ‘Unless you have believed, you will not understand’ [cf. Isa. 7: 9]—to make no mention of other places where the Sacred Page invites us to explore its rationale—he is plainly encouraging us to pay more attention to understanding, while teaching us the sort of method by which we must proceed towards it.”[8]

An unfortunate trend in American Christianity has been the steady withdrawal of theologically conservative Christians from the public square. Following the infamous Scopes Monkey Trial in July of 1925, theologically conservative Christians have made a decided turn toward anti-intellectualism. Biblical Christianity, however, has no place for an anti-intellectual faith.

To bolster this point, Anselm quotes Isaiah. He chose the Isaiah verse in keeping with his famous maxim, which I’ll mention in a minute. For the time being, however, a better Bible verse to bolster this point would be Mark 12.30: “Love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.” We are thus clearly commanded to use our thinking abilities to better understand God as an act of love.

Philosophy can show love for God because, when done correctly, philosophy is a reflection of God. Good philosophy is marked by rigorous logic and an unflinching commitment to the truth. I’ve argued here that logic is an outworking of God’s personality: Our universe is logical because its creator is logical. When we use our logical abilities to understand Christianity, we are using logical abilities which God has given us. Furthermore, all truth, whether found in the Bible or in creation, whether discovered through the natural sciences or through philosophical inquiry, is God’s truth. You won’t find truth through philosophy that God didn’t put there.

Anselm and Tertullian in Agreement

In the background of Anselm’s argument is his sole stipulation. To restate his conclusion, Anselm’s says: “I do not think that anyone deserves to be rebuked, if, after becoming well-grounded in the faith, he has conceived a desire to exercise himself in the investigation of its logic.” It’s important that Anselm says that the people who can use philosophy to learn more about Christian theology and practice are those who are already well-grounded in the faith. To become well-grounded in the faith, believers need scripture, not philosophy. Once they have a grounding in scripture, philosophy can be a valuable tool in applying principles from the Christian worldview to everyday life.

This ties into Anselm’s famous maxim which has been in the background until now: Anselm is famous for the phrase, “fides quaerens intellectum,” which comes into English as “faith seeking understanding.” In Anselm’s writings, his intellectual pursuits are not atheistic; instead, he uses philosophy to gain a better understanding of the Christian faith. Instead of allowing philosophy to lord over theology—the exact practice which Tertullian critiqued—Anselm uses philosophy to shed light on obscure areas of theology.

In the end, it seems that Anselm and Tertullian agree on at least one element of the relationship between Christian thought and practice and philosophy: According to both Anselm and Tertullian, we must not allow philosophy to alter scripture’s clear teaching. If used correctly, however, philosophy can be a valuable tool to the mature Christian.

Notes & Sources

[1] Tertullian, On Prescription Against Heretics, Ante-Nicene Fathers, trans. Peter Holmes (Peabody, MA: Hendrickson Publishers, 2012), 1.7

[2] Philip Schaff, Ante-Nicene Christianity; A.D. 100-300, History of the Christian Church, Vol. 2, 3rd ed. (Peabody, MA: Hendrickson Publishers, 2011), 819-20.

[3] For more information on Tertullian, go to: and

[4] Anselm, “Why God Became Man,” in Anselm of Canterbury; the Major Works, ed. and trans. by Brian Davies and G. R. Evans (New York, NY: Oxford University Press), 260.

[5] Ibid.


[7] Anselm, 260

[8] Ibid.

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