(This is an edited version of a paper I wrote in seminary.)
Apologetics is the task of defending the Christian faith as true, rational, and pertinent. The purpose of this post is to explain and defend presuppositional apologetics as the best method for defending Christianity.
2. Presuppositional Apologetics and Worldviews
Presuppositional apologetics tests worldviews. A worldview is “that complex of concepts that explains and gives meaning to reality from where [one stands]—given their diverse ancestries, histories, institutions and religions.”
The presuppositional method defends Christianity by recognizing its complete truthfulness. This method accepts the entirety of the Christian position as the starting point of conversation and works primarily as a negative apologetic, demonstrating the inadequacy of other worldviews. Yet it also functions as a positive apologetic, demonstrating the truthfulness of Christianity. The method holds that rationality and logic necessarily presuppose the existence God. The presuppositional apologist recognizes “the sovereign Creator and His Word as the requisite transcendental of any intellectual endeavor,” and can therefore “expose the fatal defects of all autonomous reasoning, calling unregenerate men back…to covenantal obedience in terms of God’s Word.”
Central to presuppositional apologetics is the lordship of Jesus Christ over all things. First Peter 3:15 declares, “but in your hearts honor Christ the Lord as holy, always being prepared to make a defense to anyone who asks you for a reason for the hope that is in you…” Peter argues that the foundation for making a defense of the faith is honoring Christ as Lord. The Christian must recognize the lordship of Christ as revealed in Holy Scripture in all apologetic endeavors.
The presuppositional apologist also believes that Jesus is “the truth” (John 14:6). Whoever rejects Jesus, rejects the truth. Jesus says in Matthew 12:30: “Whoever is not with me is against me.” Moral neutrality is not an option. There is an opposition between those who set their minds on the flesh and those who have their minds set on the Spirit (cf. Romans 8:7-8). Those who are not Christians are opposed to Jesus Christ, the truth incarnate.
Christians should test the worldviews of those who reject Christ. Any worldview that makes no room for Christ as the truth cannot be fully true. Such a worldview can inconsistently hold partially to the truth, but this is no product of that worldview’s inherent adequacy.
3. Testing Worldviews
We should also test Christianity because then its truthfulness will be revealed. Objective morality exists and presupposes that God is the fountain of all goodness. God reveals truth and morality to his creatures so that they can understand it from nature generally (cf. Romans 1:18ff) and from Christ and Scripture specifically (cf. 2 Timothy 3:15-17). The Christian foundation for arguing for the concept of morality across all times and cultures is God’s revelation.
Atheism cannot account for objective morality. This does not mean that atheists always act immorally, nor even that they do not claim to be moral. Rather, this objection states that morality is inconsistent with the atheistic worldview. For example, one of the popular versions of atheism is called naturalistic materialism. In this worldview, humans have evolved from simple to complex over time, and all that exists is “natural” material. All that exists can be found in the physical world. Everything is a product of blind chance and indifference.
It is, then, inconsistent for atheists to make objective moral claims. The concept of “morality” is immaterial. No one can touch or handle morality; it is an idea, a concept, a law outside of us. Or how does an atheist make sense of the laws of logic, for example? Laws of logic are immaterial. An atheist who claims all that exists is natural material cannot account for logic. An atheist cannot even account for why humans argue about right and wrong; each human is simply forced to do what they do by the laws of nature (even though the concept of the “laws of nature” is immaterial and therefore self-refuting).
Atheists typically say that it is good to be logical, yet atheists cannot account for either morality or logic. Morality, for them, is what is most preferable for individuals or communities. “What’s right for me is right for me, and what’s right for you is what’s right for you.” But if morality has no foundation outside of humanity, then it is entirely subjective. Individuals or communities become the ultimate arbiter of morality. If individuals have the right to determine morality, chaos and anarchy would be the inevitable result. If all morality is subjective, individuals could murder other people as they see fit (and this is how people currently get away with abortion). If the killer found it morally acceptable to murder someone, no one with an atheistic worldview could consistently claim this is objectively wrong because objective morality does not exist for this worldview.
If communities are the ultimate authority for morality, things like the Holocaust cannot have been objectively wrong; the Nazis were moral arbiters for their culture, and therefore they got to decide that it was right to murder over 9 million people. An atheist can claim that it is not preferable that the Holocaust happened, but ultimately it cannot be objectively wrong or evil. It may be unpleasant for an atheist, but the atheistic worldview has no foundation to make moral judgments.
4. Dealing with Religious Objections
A major criticism of the presuppositional method is that it works so long as one is dealing with atheists, but it cannot work against other religions because they can make the exact same kinds of authoritative claims. In the end, this objection argues, both positions will continually argue in circles, never reaching a real knowledge of the truth.
This objection carries a lot of weight, but it can be answered convincingly. Since God exists, what sense does it make to assume that God does not exist in order to dialogue with non-Christian theists? God is the ultimate fountain and source of all truth. To stand on his Word is to stand on the truth. If an apologist gives up the Word of God as his foundation, he gives up the standard of truth. When Christians talk with Mormons it is not simply a matter of the Bible vs. the Book of Mormon. Rather, it is the Word of God vs. the religious invention of an idolater. All people know God, yet all people suppress their knowledge of God (cf. Romans 1:18ff). Every religion besides Christianity is a false religion running around with stolen Christian truth.
If the conversation turns into arguing in circles over religious authority, the Christian can be confident that the true God’s revelation will actually get through to the opponent, even when they reject and suppress it, replacing it with a god of their own invention. The God who created the universe and everything in it is certainly powerful enough to get through to his creatures. This does not mean that all will accept God: “the natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned” (1 Corinthians 2:14). Non-Christian theists have beliefs about their god(s), but they steal from the only true religion and suppress right knowledge of God found only in that true religion.
Presuppositional apologetics is the best method for defending Christianity as true, rational, and pertinent because it recognizes the revelation of God as the ultimate foundation of truth. Jesus Christ is the truth, and he is Lord of all creation. Any position that rejects Jesus cannot ultimately be true. There is no neutral ground when it comes to Jesus. Presuppositional apologetics, then, is the most consistent way of demonstrating the truthfulness of the Christian faith.
Atheists cannot consistently account for morality and non-Christian theists borrow truth from Christianity and repackage it in a variety of forms. This is idolatry, exchanging the true God for a god made in the image of humanity (cf. Romans 1:22-23). Presuppositional apologetics is the only consistent way of defending Christianity because it is the only method which recognizes the truth about God and reality.
 I don’t like the term “presuppositional” as a descriptor for this method, but for the sake of clarity I use it throughout this post. See also K. Scott Oliphint, Covenantal Apologetics: Principles & Practice in Defense of Our Faith (Wheaton: Crossway, 2013).
 Douglas Groothuis, Christian Apologetics: A Comprehensive Case for Biblical Faith (Downers Grove: InterVarsity Press, 2011), 19. Groothuis cites Samuel Huntington, A Clash of Civilizations (New York: Simon & Schuster, 1996), 21 for this definition.
 Greg L. Bahnsen, Presuppositional Apologetics: Stated and Defended (Powder Springs: AV Press, 2011), 6.
Bahnsen, Greg L. Always Ready: Directions for Defending the Faith. Covenant Media Press, 1998.
————. Presuppositional Apologetics: Stated and Defended. Powder Springs: American Vision Press, 2011.
Oliphint, K. Scott. Covenantal Apologetics: Principles & Practices in Defense of Our Faith. Wheaton, IL: Crossway, 2013.
Van Til, Cornelius. The Defense of the Faith. Phillipsburg, NJ: Presbyterian & Reformed, 2008.
Thanks for reading. Any additional thoughts? Leave a comment below.