In the landscape of Christian apologetics, few names stand as firmly as Dr. Greg L. Bahnsen. A brilliant theologian and philosopher, Bahnsen was best known for championing and systematizing Cornelius Van Til’s presuppositional apologetics—a bold, intellectually rigorous defense of the faith that confronts unbelief at its root. Rather than merely presenting evidences for Christianity in a neutral arena, Bahnsen followed Van Til in arguing that neutrality is a myth. Every worldview begins with presuppositions—basic assumptions about reality, knowledge, and ethics. And unless those assumptions are rooted in the triune God of Scripture, they collapse into irrationality.
In this essay, we’ll examine Bahnsen’s apologetic method, how it engages with opposing worldviews like Cultural Marxism, and offer a fictional yet illustrative dialogue between Bahnsen and a Cultural Marxist. Through this, readers will grasp both the brilliance and practical effectiveness of presuppositional apologetics in contending for the faith in today’s ideological battlefield.
The Foundation: Van Til and the Transcendental Argument
Cornelius Van Til, a Dutch Reformed theologian at Westminster Theological Seminary, laid the groundwork for presuppositional apologetics in the mid-20th century. He taught that every worldview operates on foundational beliefs (presuppositions) that guide how one interprets the world. While evidential or classical apologists argue from shared “neutral” facts to the truth of Christianity, Van Til insisted that unbelievers suppress the truth in unrighteousness (Romans 1:18), making any claim to neutrality dishonest and self-defeating.
Bahnsen took this framework and sharpened it, especially through his famous “Transcendental Argument for God” (TAG). The transcendental argument claims that the very possibility of rational thought, moral obligation, and scientific inquiry presupposes the existence of the Christian God. In other words, unless Christianity is true, we couldn’t know anything at all.
Bahnsen didn’t merely claim Christianity was more reasonable than other views—he claimed it was the precondition of reason itself.
Greg Bahnsen: Scholar, Pastor, Debater
Dr. Greg Bahnsen (1948–1995) was both a rigorous scholar and a passionate pastor. He held a Ph.D. in philosophy from the University of Southern California and a Master of Divinity from Westminster Theological Seminary. His most famous debate was with atheist Gordon Stein in 1985, often hailed as a “rout” for the Christian side. In it, Bahnsen repeatedly asked Stein to account for the laws of logic, morality, and science without borrowing from a biblical worldview.
Bahnsen’s method was not to flood an opponent with facts but to expose the intellectual bankruptcy of unbelief. He called this “pushing the antithesis”—driving the unbeliever’s presuppositions to their logical conclusions to show they lead to absurdity. Then, he would contrast this with the internal coherence and explanatory power of the biblical worldview.
Understanding Cultural Marxism as a Competing Worldview
Cultural Marxism is a term used to describe the adaptation of classical Marxist theory from economic classes to cultural categories. Instead of the proletariat versus the bourgeoisie, Cultural Marxists divide society into oppressed and oppressor groups based on race, gender, sexuality, and other identity categories. This ideology sees traditional Western institutions—family, church, nation, capitalism—as oppressive systems to be deconstructed.
It borrows heavily from postmodern assumptions: truth is subjective, language is power, and morality is a social construct. In this way, Cultural Marxism is not merely political—it’s religious in nature. It offers an origin story (oppression), a doctrine of sin (privilege), a redemption plan (social justice activism), and a final judgment (cancellation or liberation).
Bahnsen’s method is well-equipped to address such systems because it exposes their internal contradictions and moral parasitism. Cultural Marxism depends on moral indignation—but without a fixed standard of morality, its outrage is arbitrary.
The Method in Practice: Bahnsen’s Core Strategy
Bahnsen’s approach follows this structure:
- Identify the opponent’s presuppositions. What do they believe about reality, knowledge, and ethics?
- Expose the internal inconsistency of their worldview. Can their worldview provide the preconditions of intelligibility (logic, science, morality)?
- Demonstrate that only the Christian worldview is internally coherent and provides a basis for rational thought, morality, and meaning.
- Call for repentance and faith in Christ as the only true foundation for knowledge and life.
Bahnsen would often challenge the unbeliever to justify their reasoning, moral indignation, or scientific inquiry apart from the triune God. His goal was not to “win an argument” but to expose the spiritual nature of rebellion against God.
Dialogue: Greg Bahnsen Meets a Cultural Marxist
Let us now imagine a fictional but realistic conversation between Greg Bahnsen and “Liam,” a young Cultural Marxist university student.
Scene: A moderated panel discussion at a college campus. The topic is “Truth, Justice, and Oppression.”
Liam: Dr. Bahnsen, as a straight, white, Christian male, you represent systems of oppression that have marginalized people for centuries. The Christian worldview has been used to justify slavery, colonialism, and patriarchy. Isn’t it time we dismantle those structures and pursue a more inclusive and equitable future?
Bahnsen: Liam, before we talk about dismantling structures, may I ask—on what basis do you declare something oppressive or unjust?
Liam: Oppression is when one group uses power to marginalize another. Justice means equal rights and recognition for all.
Bahnsen: I appreciate your concern for justice, but let me press you: Is justice an objective moral standard? Or is it socially constructed?
Liam: Morality is constructed by society. What we consider “right” or “wrong” is shaped by cultural context.
Bahnsen: If morality is socially constructed, then Nazi Germany’s moral code was just as valid as any other society’s, correct?
Liam: Well, no. The Nazis were objectively wrong.
Bahnsen: But you just said morality is socially constructed. The Nazis believed what they were doing was moral. If there’s no higher, objective standard, then you have no grounds to condemn them—except personal or cultural preference.
Liam (frustrated): But we know murder and genocide are wrong!
Bahnsen: Yes, we do. But I ask you to account for that knowledge. Why is murder wrong in a universe that is the product of blind chance, where humans are just evolved animals?
Liam: Because it harms others. It causes suffering.
Bahnsen: And why is suffering wrong? Lions cause suffering to zebras every day. Are they immoral? On your worldview, morality is just evolutionary conditioning. There’s no real “ought,” just “is.” You’re borrowing from the Christian worldview to make your moral claims.
Liam (pause): So you think Christianity has a monopoly on morality?
Bahnsen: Christianity provides the only rational basis for objective morality. God is the lawgiver. His character defines good and evil. Without Him, moral claims collapse into preference. And ironically, your outrage at injustice only makes sense if Christianity is true.
Liam: But your faith has hurt people.
Bahnsen: Sinful humans have misused Christianity—just as they’ve misused medicine or government. But that doesn’t invalidate the truth of the gospel. It proves that man is sinful and needs redemption. Jesus Christ alone offers that, not through revolution, but through repentance and grace.
The Power and Precision of Presuppositionalism
This dialogue demonstrates the power of Bahnsen’s method. He didn’t start with evidences or emotional appeals. He questioned Liam’s worldview at the presuppositional level. By doing so, he forced Liam to see that his own moral outrage was inconsistent with his relativistic beliefs. Bahnsen didn’t dodge Liam’s accusations—he answered them with clarity and redirected the conversation to the gospel.
Presuppositional apologetics may seem confrontational, but it is deeply pastoral. It takes seriously the biblical truth that the unbeliever suppresses the knowledge of God, yet it calls that same person to repentance with grace and truth.
A Timely Tool for Today’s Church
In an age where relativism, Cultural Marxism, and moral confusion dominate our institutions, Bahnsen’s method is not just useful—it is necessary. Christians must learn to think presuppositionally. This means:
- Asking unbelievers how they account for the things they take for granted: reason, morality, human dignity.
- Recognizing that every worldview is religious at heart—it makes claims about ultimate reality.
- Proclaiming the lordship of Christ over all areas of life, not just “religious” ones.
Bahnsen equips believers to stop playing defense and start challenging the intellectual foundations of unbelief. As he often said, “The atheist can’t find God for the same reason a thief can’t find a policeman.”
Conclusion
Greg Bahnsen stood boldly for the authority of Scripture and the lordship of Christ in all areas of life. His application of Van Til’s presuppositional apologetics was not mere theory—it was a weapon against the idols of the age. As Cultural Marxism and other secular ideologies seek to reshape society, Christians must be prepared to give an answer—not just with evidence, but with a challenge to the very assumptions behind unbelief.
Only the Christian worldview offers coherence, hope, and salvation. And as Bahnsen tirelessly proclaimed, without Christ, we lose the ability to reason, to judge right from wrong, and ultimately, to live.
S.D.G.,
Robert Sparkman
rob@basedchristianity.org
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