Christianity and Logic


There are many Christians today who think that logic is unnecessary, useless, or unimportant. According to them, we should spend our time on bigger and better things, like reaching people for Jesus. Some would argue that we should not waste our time studying logic, but instead, we should study the Word of God. Some even piously claim that “logic is not the gospel, so what’s the point?” The truth is that many modern churchgoers engulf themselves in irrational thought and dismiss logic altogether.

This kind of thinking is certainly present, if not predominant, in churches today, and it expresses a deep lack of understanding of what logic is and why it is necessary. Perhaps this negative view of logic stems from the deeply rooted anti-intellectualism of many evangelical Christians who seek an emotional high in their religious experience rather than a deeper understanding of the Word of God. They simply do not understand the relationship between logic and the Bible.

This anti-intellectualism can often be seen in churches that downplay the importance of sound doctrine and do not concern themselves with harmonizing or systematizing God’s word. When confronted about the state of irrationalism that has crept into modern Christianity we find that many professing Christians disparage and even dismiss logic. However, any attempt to disparage or dismiss logic is self-refuting for the very reason that one must use logic in order to make their own argument against logic intelligible. As Dr. John Robbins notes, “The opponents of logic must use the law of contradiction in order to denounce it. They must assume its legitimacy, in order to declare it illegitimate. They must assume its truth, in order to declare it false. They must present arguments if they wish to persuade us that argumentation is invalid. Wherever they turn, they are boxed in.”[i] Thus, any attack on logic is undermined by the antagonist’s own use of it. This is simply unavoidable.

Many who desire to throw logic out the window in pursuit of other “nobler” endeavors do not realize that logic is fundamental to all disciplines, all thought, and all language. Those who would argue that we should study our Bibles instead of wasting our time with logic miss the fact that the correct method of Biblical interpretation, that is to interpret Scripture in the light of Scripture, requires the most fundamental law of logic, the law of non-contradiction. Those who would argue that logic is not the gospel do not understand that affirming and proclaiming the gospel requires the laws of logic, such as the law of the excluded middle. If logic therefore, is required for the affirmation and proclamation of the most basic–indeed all–Christian truths, then every Christian should understand logic and know how to use it.

What is Logic?

A study in logic may be difficult at first but even the most basic understanding will prove beneficial. In order for a person to reason correctly and think rationally, they must think logically. Dr. Gordon Clark defined logic as the “science of necessary inference.”[ii] Logic is the science of correct thinking and therefore, it may be explained as the correct process of reasoning.

In formal logic, there are three fundamental laws which are the law of contradiction, the law of identity, and the law of the excluded middle. These laws are deduced from Scripture, which allows us to account for them as universal and unchanging principles. The law of contradiction, which states, A cannot be A and not A at the same time and in the same respect is revealed in scripture as part of God’s eternal character and nature, “for he cannot deny [contradict] himself” (2 Timothy 2:13)[iii]. In this verse the law is expressed in the form of a proposition. In the symbolic notation however, “A” can represent either a proposition or a word. Therefore, the law of contradiction is embedded into every word of scripture. When Genesis 1:1 declares, “In the beginning, God created the heavens and the earth” it does not mean “In the beginning, God dismantled the heavens and the earth” for that would contradict the proposition of divine revelation. The word “created” does not mean “dismantled” and vice versa. Each word has a specific meaning and although a word may have more than one meanings in general, it cannot have more than one meaning in any proposition. Clark writes, “A word that means everything means nothing. In order for a word to mean something, it must also not mean something.”[iv]

The law of identity (A is A), which holds that everything has a specific nature, is expressed in God’s name, “I AM WHO I AM” (Exodus 3:14). Everything exists as something in particular to itself, and everything has specific characteristics that make it what it is. For example, God is holy, righteous, sovereign, loving, and good. God’s identity however includes all his specific traits and not just the ones mentioned. This law is crucial because it means that God has a definite nature and is therefore knowable.

The law of the excluded middle, also known as the principle of the excluded third (principium tertii exclusi), holds that a proposition is either true or its negation is true; there is no third option. This law is deduced from Jesus’ own words to the Father, “your word is truth” (John 17:17). In this verse Jesus affirmed for us that all propositional revelation is true thereby upholding the law of the excluded middle.

It is precisely because these laws of logic are embedded in Scripture that the Christian can establish from an epistemological standpoint that they are fixed and universal “laws.” Epistemology seeks to answer the question “how do we know?” Scripture is the answer. Without the epistemology of scripture, we cannot account for the laws of logic and it is for that reason that Scripture rather than logic itself is chosen as the Christian axiom. We agree with Dr. Clark that “Scripture, the written words of the Bible, is the mind of God. What is said in Scripture is God’s thought.”[v] This is how we know that the laws of logic are fixed and do not change, because “the word of our God will stand forever” (Isaiah 40:8). Likewise, we also know that they are universal because “he upholds the universe by the word of his power” (Hebrews 1:3). In other words, we know these laws of logic are “laws.”

Although it is true that all rational thinking requires logic, it is impossible to establish an epistemological foundation for logic strictly from the mind of man, for the laws are universal principles, and the mind of man has no universal significance at all. The Christian must also understand that logic is not descriptive of human thinking–it is not psychology–but is rather prescriptive for all human thought. This means that logic does not describe how a person does think, but rather how a person should think if they are to think correctly. The laws of logic could never be derived from a description of how people think because many people tend to think irrationally, illogically, often contradicting each other and even themselves.

The laws of logic can, however, be derived from a description of how God thinks because He is always consistent, rational, logical and never errs in his reasoning. Logic then is, as Dr. Clark wrote, “the characteristic of God’s thinking. It is not subsequent temporally, for God is eternal and there never was a time when God existed without thinking logically.”[vi] God cannot lie because it is inconsistent with His eternal character and He will not and cannot contradict Himself. “The Glory of Israel will not lie or change His mind; for He is not a man that He should change his mind” (1 Sameul 15:29). This is just one verse of many that provide us a description of the nature and character of God. This is the way in which God thinks and it is the way in which we ought to think. It would be fallacious, however, for one to derive a prescriptive ought statement from the descriptive is statement of God’s nature and character. Fortunately, the Christian is not merely left with a description of the way in which God thinks but we are also given a prescription for the way in which we ought to think. Scripture tells us, “You, therefore, must be perfect, as your heavenly Father is perfect” (Matthew 5:48). Paul also exhorts us to “be imitators of God, as beloved children,” (Ephesians 5:1).

It should be clear then that the Christian is able to account for the laws of logic from an epistemological foundation that is consistent and rationally justifiable within the Christian worldview.

Our Moral Obligation

It may come as a surprise to many Christians to learn that we have a moral obligation to think logically. Perhaps this is because they have not considered carefully that it is impossible to obey God if our thinking is illogical. We often associate sinful thoughts with the vices of lust or hatred, but the truth is that all sin originates in our thinking. “Although adultery and theft are commonly regarded as overt actions, their origin is in our thinking. Sin is the result of intellectual error.”[vii] Clark was correct then, to point to such verses as Proverbs 23:7– “As a man thinks in his heart, so is he”–in order to point out that “sin is first of all mental and only afterward overt.”[viii]

Some might find this disturbing and may wish to separate logic from morality, but logic is necessary for morality as well because without logic there can be no distinction between deception and truth, good and evil, right and wrong. It is no wonder then that the Scriptures are logically consistent. If this were not the case, then we would not be able to discern truth from error. If God’s thinking is logically consistent and the Scriptures are part of the mind of God, then it is impossible to obey scriptural commands if we contradict the Bible in the way we think.

The reality is that we often do not stop to consider just how intellectually disobedient we can be in our thinking. It is important to realize that it is impossible to love God with all our mind if we are illogical. How can we surrender every thought captive to the Lordship of Christ (2 Corinthians 10:5) if our thinking does not reflect the logical consistency of Scripture? The inescapable result of failing in this area is compromise, error, and sin. We inevitably begin to adopt worldly and secular thinking which is firmly opposed to the Word of God. We should recognize that every attack from the enemy is an attack on the Word of God. A clear example of this can be seen in the current debates over same-sex marriage and abortion.

Christ asserts that marriage is between a man and a woman (Matthew. 19:4-5), so we stand in direct defiance if we insist that same-sex marriage is morally good. When we likewise insist that a woman has the right to abort their unborn children then we defy God and advocate the murder of children on the altar of convenience and shame. Those who advocate such positions stand in direct opposition to Christ and His Word. Professing Christians who hold such positions display and an incredible amount of logical inconsistency and as a result, have no basis for believing that Jesus died on the cross for their sins. If they do not believe the Bible when it speaks on the issue of marriage, the sin of homosexuality, and the life of an unborn child, then what basis do they have for believing the truth of the cross? How convenient it must be to arbitrarily pick and choose what suits us. Such advocates of logical inconsistency would be hard-pressed to provide a rational reason for believing that the gospel is true while rejecting its source as unreliable when it doesn’t suit them.

Accounting for Logic

The unbeliever cannot account for logic in his own worldview and therefore cannot account for his ability to think rationally. The challenge has been made many times to unbelievers to account for logic in their own worldview and it has always fallen short or gone unanswered. Never has an adequate response been given. In formal debates, the challenge is often ignored by the unbeliever, yet the challenge demands an answer because debates presuppose logic.

The unbeliever is required to use logic in order to make his argument against Christianity consistent and intelligible, but only the Christian worldview can account for logic. He is therefore required to rob the Christian worldview in order to make his argument against Christianity intelligible

Some argue that logic is merely a description of nature. Logic, however, cannot be accounted for in nature because logic concerns thinking and governs how we ought to think. The 18th century Scottish Philosopher David Hume identified the impossibility of deriving an “ought” statement from an “is” statement. Nature can only provide a description of what is but cannot provide a prescription of what ought to be, so it cannot tell us how we ought to think. Logic is also immaterial and conceptual while nature is just the opposite. This proves to be an impossible hurdle for the atheistic materialist to rise above.

Due to the materialist’s inability to account for an immaterial law, many try to adopt a form of rationalism. Rationalism is the theory that all knowledge comes from logic alone, apart from the senses and revelation. The rationalist assumes the laws of logic but ultimately fails to account for them. This is problematic because in order for a worldview to be complete it must be able to account for the laws of logic which are a precondition of intelligibility. Because the Rationalist cuts himself off from divine revelation, he isolates himself in his thinking. He attempts to arrive at knowledge from logic alone but has no epistemological foundation for the universal laws logic because they are not descriptive of his own thinking but rather prescriptive of how he ought to think. If he supposes that all knowledge comes from logic but is unable to provide a foundation of knowledge by which he can know the laws of logic as prescriptive, independent, and invariant laws of thought, then he is hopelessly lost. One cannot navigate from logic alone to any propositional knowledge or truth.

We will further demonstrate the failure of rationalism by attacking its first premise. Rationalism says that all knowledge comes from logic alone, but this knowledge claim itself cannot be inferred from logic alone. Although the laws of logic are communicated as propositions which require the laws of logic in order to be intelligible, the laws themselves provide no additional content about reality or truth. The laws of logic can only be applied to how we think. They only tell us how we should think but provide no content of thought. The rationalist must show that the laws of logic provide all the necessary content of thought and that this content can only be derived from the laws themselves and nothing else. The law of contradiction is a universal rule of thought but the law itself cannot tell us what is universal.

If rationalism cannot know its first premise by its own method, then it is shown to be self-refuting and fails as a theory of knowledge. No self-contradictory epistemological foundation can account for the law of contradiction. If rationalism fails as a theory of knowledge, then there is nothing that can be known on rationalism. If one cannot know anything on rationalism, then it cannot account for the universal laws of logic which exist outside the mind of the rationalist. We need more than what rationalism can offer. We need divine revelation from God.

Many reject the epistemology of Christianity which accounts for logic in the Word of God and instead turn to Empiricism. This comes as no surprise since the rebellious mind is hostile towards God and rejects that “the fear of the LORD is the beginning of knowledge” (Proverbs 1:7).

When 17th-century rationalists saw the shortcomings of assuming logic alone, the world shifted towards empiricism. Today empiricism may be regarded as the most widely held epistemology and it is the underlying presupposition for many arguments against Christianity. When unbelievers argue that there is no empirical evidence for God they are presupposing the epistemology of empiricism. But it is impossible to even make such an argument intelligible without presupposing the laws of logic. Using logic is necessary for such argumentation but presupposing the truth of empiricism is problematic because logic cannot be accounted for empirically. Empiricism holds that all knowledge comes through the senses, but the laws of logic have never been observed by any of the senses since they are conceptual. Even if one were to make an appeal that every perceived contradiction they have ever encountered has been false, they still have no hope whatsoever of asserting the laws of non-contradiction on empiricism. This is, in part, due to the fact that the law is universal, but their experience is limited. There simply is no way to establish a universal law by one’s limited experience. Any attempt to do so would be committing the fallacy of induction because the induction could never be completed.

Another aspect of the laws of logic that must be established is the fact that the laws are timeless and fixed. There is simply no way to establish the timeless nature of a law on the basis of one’s own limited past experience and there is no way to empirically verify that the future will reflect the past because the future has not been observed. There is no basis for saying that the law of contradiction will stand tomorrow on an empirical foundation. No universal timeless law can ever be empirically verified because no one has experienced all the past or any of the future.

When the empiricist states, “all knowledge comes through the senses” he does not mean that “no knowledge comes through the senses” for that would contradict his claim. He is, therefore, using the law of non-contradiction in order to make his claim intelligible. It is ironic then that logic is necessary to define empiricism and give it meaning yet at the same time it requires that empiricism be regarded as false. The claim that all knowledge comes through the senses requires the application of the law of non-contradiction in order that it might be intelligible and understood yet the claim is self-contradictory. The claim that all knowledge comes through the senses is a knowledge claim that has not been observed by the senses. Empiricism has never been observed and cannot be empirically verified. Not only does empiricism fail to account for logic but the same logic that is necessary for its own definition requires that empiricism itself be rejected by the rational mind.

Many people attempt to combine rationalism with empiricism to overcome the shortcomings of both. Yet rationalism cannot deduce anything from logic alone, ultimately failing to account for logic itself, and empiricism cannot yield any knowledge or propositions from the senses, including the laws of logic. Just as the unbelievers require air to breathe with which to curse God, so also, they require the laws of logic in order to make their case against God intelligible. By way of analogy we can look to a group of angry protestors in Wisconsin who recently found themselves in an embarrassing situation. The headline reads, “Awkward: Protesters Fail to Inflate Coal Plant Balloon with Renewable Energy.”[ix] The group of unhappy activists was protesting Madison Gas and Electric’s new rates, complaining that it diminished consumer interest in renewable energy. To make their case loud and clear, they inflated a blow-up coal plant balloon using nothing but “renewable energy” while chanting “Coal has to go!” Unfortunately, the blow-up coal plant collapsed because their batteries ran out of power and their solar panel did not produce enough energy to keep it inflated. The group later admitted that they would normally inflate the prop with electrical wall outlets or gas-powered generators. The irony and foolishness of the situation aren't difficult to see. The energy company they were protesting against provides them the energy required to inflate the prop in their protest. Without that energy source, they can’t even inflate their prop. Atheists find themselves in a similar predicament. Without logic, they cannot make their case against Christianity, yet only the Christian worldview can account for logic. The Christian God must first provide man the ability to reason, and only then can he suppress the truth in unrighteousness (Romans 1:18).

Logic and knowledge

Many Christians don’t recognize man’s dependence on God for knowledge and how this relates to logic. Without logic, knowledge would be impossible because we could never know what is true; no distinction between truth and error could ever be made. The connection between man’s dependence on logic for knowledge and man’s dependence on God for knowledge is easily established in the person of Jesus Christ.

“In the first chapter of the Gospel of John, John wrote, ‘In the beginning was the Logos, and the Logos was with God, and the Logos was God.’ The Greek word Logos is usually translated Word, but it is better-translated Wisdom or Logic. Our English word logic comes from this Greek word logos. John was calling Christ the Wisdom or Logic of God. In verse nine, referring again to Christ, he says that Christ is ‘The true light’ who lights every man.”[x]

Jesus is the Logos--the Logic of God--that lights every man with knowledge. This is why the Scriptures tell us that in Christ Jesus "are hidden all the treasures of wisdom and knowledge" (Colossians 2:3). Here is the heart of Christian epistemology: All wisdom and knowledge are hidden in Christ. The fact that all knowledge is hidden in Christ means that man cannot search it out anywhere else. If Christ does not illuminate the mind of man, then man can know nothing at all. And because our ability to think rationally requires logic, man cannot even reason or think rationally apart from Christ, the Logic of God.

Rejecting Logic

The desire of the unbeliever to reject God may also cause him to reject logic as well. This should not come as a surprise to us since God has made "foolish the wisdom of the world" (1 Corinthians. 1:20). If the unbeliever forfeits logic then he has already lost the debate because all debates, all rational discourse, and all communication, presupposes logic. Without logic, the unbeliever cannot even make his case against Christianity intelligible.

Let us return to our unhappy protesters and consider for a moment that the coal plant balloon represents an argument against the company they were protesting. The protesters were protesting the energy company because of its non-renewable energy, yet they required that same non-renewable energy to inflate their balloon. Likewise, some atheists reject logic in order to make their arguments against Christianity, yet they require logic to make their arguments intelligible. Theoretical physicist and atheistic propagandist Stephen Hawking is one such example. Hawking writes: “Because there is a law such as gravity, the universe can and will create itself from nothing.”[xi] In order to argue for a self-created universe, one must reject the law of non-contradiction. For something to be its own creator and its own creation, it must exist and not exist at the same time and in the same sense. According to Aristotle, “The same attribute cannot at the same time belong and not belong to the same subject and in the same respect.”[xii] R. C. Sproul also notes that “for something to create itself, or to be its own effect as well as its own cause, it would have to exist before it existed. The universe, to be self-created, would have to be before it was. Stated in terms of the law of non-contradiction, the universe would have to be and not be at the same time and in the same relationship.”[xiii]

Hawking must reject the law of non-contradiction in order to argue for a self-created universe, but it is impossible for him to make his argument intelligible apart from the law of non-contradiction. That is because every word in his argument has definite and specific meaning.  As Dr. John Robbins wrote, “Each word has a definite meaning. In order to have a definite meaning, a word must not only mean something, it must also not mean something.”[xiv] When Hawking argues that “the universe can and will create itself from nothing,” he does not intend for us to understand that “the universe cannot and will not create itself from nothing,” for that would contradict his claim. The word “can” does not mean “cannot” and the word “will” does not mean “will not.” He is, therefore, rejecting the law of non-contradiction to make his argument while at the same time using the law of non-contradiction to make his argument intelligible. His argument is self-refuting. No rational person could ever accept such a position. Unfortunately, atheists make arguments like this all the time. However, if they insist on making logical blunders or advancing self-refuting arguments or dismissing logic altogether in order to maintain the position of atheism then so be it. Christians have nothing to fear, for “let God be true but every man a liar. As it is written: 'That you may be justified in your words, and may overcome when you are judged' " (Romans 3:4). Since the Bible alone can properly account for logic the unbeliever is forced steal from the Christian worldview in order to argue against it. This is the inevitable tragedy of every argument raised against the knowledge of Christ. “The fool says in his heart, ‘There is no God’” (Psalms 14:1).


[i] John W. Robbins, “Why Study Logic?”, The Trinity Review (July/August, 1985)

[ii] Gordon H. Clark, Logic, Fourth ed. (Unicoi, Tennessee: Trinity Foundation, 2004), 162.

[iii] Scripture references are ESV unless otherwise noted. All emphases in Scripture quotations are mine.

[iv] “Chapter 5 Logic.” In Defense of Theology, by Gordon H. Clark and John W. Robbins, Trinity Foundation, 2007, p. 48.

[v] Gordon H. Clark, “God and Logic,” The Trinity Review (November/December, 1980), edited by John W. Robbins, 4.

[vi] Clark, “God and Logic,” 3.

[vii] Gordon H. Clark, “The Theologian’s Besetting Sin,” The Trinity Review (March/April, 1992), edited by John W. Robbins.

[viii] Clark, “The Theologian’s Besetting Sin,”

[ix] Gutfield, Greg. "Awkward: Protesters Fail to Inflate Coal Plant Balloon With Renewable Energy." Fox News. FOX News Network, 16 Oct. 2016. Web. 24 June 2017. <>.

[x] Robbins, “Why Study Logic?”, 2.

[xi] Roberts, Laura. "Stephen Hawking: God Was Not Needed to Create the Universe." The Telegraph. September 2, 2010. Accessed November 10, 2014. Emphasis mine

[xii] Robbins, “Why Study Logic?”, 3.

[xiii] Sproul, R.C. "Self-Creation." In Defending Your Faith, 205. Wheaton, Illinois: Crossway Books, 200

[xiv] Robbins, “Why Study Logic?”, 4.