Augustine on Faith and Reason Part I

Sanctify them in the truth; your word is truth.”

- John 17:17

Any presentation of Trinitarian doctrine inevitably leads to questions about logic, contradictions, and so forth. Opponents of orthodox Christianity often assert that the doctrine of the Trinity is a contradiction because it affirms both a oneness and a threeness to God. Others say that even though the doctrine of the Trinity is not a formal contradiction, they cannot believe it because they cannot understand it. Still others remain orthodox Christians and believe the doctrine while nevertheless affirming that it is a contradiction. For such people, faith is believing the unbelievable, holding as true in the heart what the mind cannot accept.

Clearly, all of these positions are wrong, for while Christians have always believed that some truths transcend our full understanding, Christian truth is never irrational. God’s Word, today’s passage reveals, is truth, and truth cannot be selfcontradictory. If it were otherwise, we could not know anything. If truth is contradictory, the word truth loses all meaning. Our Lord calls us to love Him with our minds (Matt. 22:37). We love Him with our minds by studying His revelation in nature and in Scripture. Furthermore, this love seeks to resolve apparent contradictions while attempting to understand how all truth fits together in harmony.

So, while the doctrine of the Trinity says God is one and three at the same time, it is not a contradiction because it does not say God is one and three in the same sense. We may be unable to understand fully how this all fits together, but the doctrine does not violate the standards of biblical truth or logic. In fact, if the Lord’s “greatness is unsearchable” (Ps. 145:3), we should expect that there will be some things about Him that we will not fully grasp. Still, to say that we must believe things we cannot fully understand is different from saying that we must believe things that are inherently irrational. God calls us to the former but never the latter.

Augustine understood this point well and often addressed principles of epistemology (how we know what we know). His conviction was that God’s revelation is the prerequisite for truth: if human beings are to know anything, the Lord must illumine our minds. The source of this view is Scripture, which says that those outside God’s kingdom are darkened in their understanding (Eph. 4:17–18).

Coram Deo

Whenever human beings come to a knowledge of the truth, it is because the Lord has illumined His revelation. Even impenitent sinners sometimes submit to His natural revelation, but they do not do so consistently. This explains why even the smartest people can teach and do the dumbest things. As Christians, our minds have been awakened to the truth of God, giving us an advantage over those who remain darkened in their understanding.

Passages for Further Study

1 Kings 3:1–15
Job 28:20–28
Psalm 92:5–9
1 John 5:20

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