The Existence of God

If theology is the study of God and his works, then the existence of God is as foundational to theology as the existence of rocks is to geology. Two basic questions have been raised regarding belief in God’s existence: (1) Is it true? (2) Is it rationally justified (and if so, on what grounds)? The second is distinct from the first because a belief can be true without being rationally justified (e.g., someone might irrationally believe that he’ll die on a Thursday, a belief that turns out by chance to be true). Philosophers have grappled with both questions for millennia. In this essay, we will consider what the Bible says in answer to these questions, before sampling the answers of some influential Christian thinkers.

Scripture and the Existence of God

The Bible opens not with a proof of God’s existence, but with a pronouncement of God’s works: “In the beginning God created the heavens and the earth.” This foundational assertion of Scripture assumes that the reader not only knows already that God exists, but also has a basic grasp of who this God is. Throughout the Old Testament, belief in a creator God is treated as normal and natural for all human beings, even though the pagan nations have fallen into confusions about the true identity of this God. Psalm 19 vividly expresses a doctrine of natural revelation: the entire created universe ‘declares’ and ‘proclaims’ the glorious works of God. Proverbs tells us that “the fear of the Lord” is the starting point for knowledge and wisdom (Prov. 1:7; 9:10; cf. Psa. 111:10). Denying God’s existence is therefore intellectually and morally perverse (Psa. 14:1; 53:1). Indeed, the dominant concern throughout the Old Testament is not whether God is, but who God is. Is Yahweh the one true God or not (Deut. 4:35; 1Kgs. 18:21, 37, 39; Jer. 10:10)? The worldview that provides the foil for Hebrew monotheism is pagan polytheism rather than secular atheism.

This stance on the existence of God continues into the New Testament, which builds on the foundation of the uncompromising monotheism of the Old. In his epistle to the Romans, the apostle Paul insists that God’s “eternal power and divine nature” are clearly perceived from the created order itself. Objectively speaking, there can be no rational basis for doubt about the existence of a transcendent personal creator, and thus there can be no excuse for unbelief (Rom. 1:20). Endued with a natural knowledge of our creator we owe God our honor and thanks, and our failure to do so serves as the primary basis for the manifestation of God’s wrath and judgment. The apostle’s robust doctrine of natural revelation has raised the question of whether anyone can truly be an atheist. The answer will depend, first, on how “atheist” is defined, and second, on what precisely Paul means when he speaks of people “knowing” God. If the idea is that all men retain some genuine knowledge of God, despite their sinful suppression of natural revelation, it’s hard to maintain that anyone could completely lack any cognitive awareness of God’s existence. But if “atheist” is defined as someone who denies the existence of God or professes not to believe in God, Romans 1 not only allows for the existence of atheists – it effectively predicts it. Atheism might then be understood as a form of culpable self-deception.

Paul’s convictions about natural revelation are put to work in his preaching to Gentile audiences in Lystra and Athens (Acts 14:15–17; 17:22–31). Paul assumes not only that his hearers know certain things about God from the created order but also that they have sinfully suppressed and distorted these revealed truths, turning instead to idolatrous worship of the creation (cf. Rom. 1:22–25). Even so, his appeals to general revelation are never offered in isolation from special revelation: the Old Testament Scriptures, the person of Jesus Christ, and the testimony of Christ’s apostles.

Elsewhere in the New Testament, the question of the existence of God is almost never explicitly raised, but rather serves as a foundational presupposition, an unquestionable background assumption. One exception would be the writer to the Hebrews, who remarks that “whoever would draw near to God must believe that he exists and that he rewards those who seek him” (11:6). In general, the New Testament is concerned less with philosophical questions about the existence of God than with practical questions about how sinners can have a saving relationship with the God whose existence is obvious. As in the Old Testament, the pressing question is never whether God is, but who God is. Is Jesus Christ the revelation of God in human flesh or not? That’s the crux of the issue.

Arguments for the Existence of God

Consider again the two questions mentioned at the outset. (1) Is belief in God true? (2) Is it rationally justified? One appealing way to answer both questions affirmatively is to offer a theistic argument that seeks to infer God’s existence from other things we know, observe, or take for granted. A cogent theistic argument, one assumes, would not only demonstrate the truth of God’s existence but also provide rational justification for believing it. There is a vast literature on theistic arguments, so only a sampling of highlights can be given here.

The first generation of Christian apologists felt little need to argue for God’s existence for the same reason one finds no such arguments in the New Testament: the main challenges to Christian theism came not from atheism, but from non-Christian theism (Judaism) and pagan polytheism. Not until the medieval period do we find formal arguments for the existence of God offered, and even then the arguments do not function primarily as refutations of atheism but as philosophical meditations on the nature of God and the relationship between faith and reason.

One of the most famous and controversial is the ontological argument of St. Anselm (1033–1109) according to which God’s existence can be deduced merely from the definition of God, such that atheism leads inevitably to self-contradiction. One distinctive of the argument is that it relies on pure reason alone with no dependence on empirical premises. Various versions of the ontological argument have been developed and defended, and opinion is sharply divided even among Christian philosophers over whether there are, or even could be, any sound versions.

Cosmological arguments seek to demonstrate that that the existence of the universe, or some phenomenon within the universe, demands a causal explanation originating in a necessary first cause beyond the universe. St. Thomas Aquinas (1225–1274) famously offered “Five Ways” of demonstrating God’s existence, each of which can be understood as kind of cosmological argument. For example, one of the Five Ways argues that any motion (change) has to be explained by some mover (cause).  If that mover itself exhibits motion, there must be a prior mover to explain it, and because there cannot be an infinite regress of moved movers, there must be an original unmoved mover: an eternal, immutable, and self-existent first cause. Other notable defenders of cosmological arguments include G. W. Leibniz (1646–1716) and Samuel Clarke (1675–1729), and more recently Richard Swinburne and William Lane Craig.

Teleological arguments, which along with cosmological arguments can be traced back to the ancient Greeks, contend that God is the best explanation for apparent design or order in the universe. Simply put, design requires a designer, and thus the appearance of design in the natural world is evidence of a supernatural designer. William Paley (1743–1805) is best known for his argument from analogy which compares functional arrangements in natural organisms to those in human artifacts such as pocket watches. While design arguments suffered a setback with the rise of the Darwinian theory of evolution, which purports to explain the apparent design of organisms in terms of undirected adaptive processes, the so-called Intelligent Design Movement has reinvigorated teleological arguments with insights from contemporary cosmology and molecular biology while exposing serious shortcomings in naturalistic Darwinian explanations.

In the twentieth century, the moral argument gained considerable popularity, not least due to its deployment by C. S. Lewis (1898–1963) in his bestseller Mere Christianity. The argument typically aims to show that only a theistic worldview can account for objective moral laws and values. As with the other theistic arguments there are many different versions of the moral argument, trading on various aspects of our moral intuitions and assumptions. Since such arguments are typically premised on moral realism—the view that there are objective moral truths that cannot be reduced to mere human preferences or conventions—extra work is often required to defend such arguments in a culture where moral sensibilities have been eroded by subjectivism, relativism, and nihilism.

Cornelius Van Til (1895–1987) gained some notoriety for his forceful criticisms of the “traditional method” of Christian apologetics which capitulated to “autonomous human reason.” Van Til held that any respectable theistic argument ought to disclose the undeniability of the triune God revealed in Scripture, not merely a First Cause or Intelligent Designer. He therefore advocated an alternative approach, centered on a transcendental argument for the existence of God, whereby the Christian seeks to show that human reason, far from being autonomous and self-sufficient, presupposes the God of Christianity, the “All-Conditioner” who created, sustains, and directs all things according to the counsel of his will. As Van Til put it, we should argue “from the impossibility of the contrary”: if we deny the God of the Bible, we jettison the very grounds for assuming that our minds have the capacity for rational thought and for reliable knowledge of the world.

Since the renaissance of Christian philosophy in the second half of the twentieth century, there has been renewed interest and enthusiasm for the project of developing and defending theistic arguments. New and improved versions of the classical arguments have been offered, while developments in contemporary analytic philosophy have opened up new avenues for natural theology. In his 1986 lecture, “Two Dozen (or so) Theistic Arguments,” Alvin Plantinga sketched out an entire A to Z of arguments for God, most of which had never been previously explored. Plantinga’s suggestions have since been expanded into a book-length treatment by other philosophers. The discipline of Christian natural theology is thriving as never before.

Basic Belief in the Existence of God

Still, are any of these arguments actually needed? Does confidence about God’s existence have to be funded by philosophical proofs? Since the Enlightenment, it has often been held that belief in God is rationally justified only if it can be supported by philosophical proofs or scientific evidences. While Romans 1:18–21 has sometimes been taken as a mandate for theistic arguments, Paul’s language in that passage suggests that our knowledge of God from natural revelation is far more immediate, intuitive, and universally accessible.

In the opening chapters of his Institutes of the Christian Religion, John Calvin (1509–1564) considers what can be known of God apart from special revelation and asserts that a natural knowledge has been universally implanted in mankind by the Creator: “There is within the human mind, and indeed by natural instinct, an awareness of divinity” (Institutes, I.3.1). Calvin speaks of a sensus divinitatis, “a sense of deity,” possessed by every single person in virtue of being created in God’s image. This internal awareness of the Creator “can never be effaced,” even though sinful men “struggle furiously” to escape it. Our implanted natural knowledge of God can be likened in some respects to our natural knowledge of the moral law through the God-given faculty of conscience (Rom. 2:14-15). We know instinctively that it’s wrong to lie and steal; no philosophical argument is needed to prove such things. Similarly, we know instinctively that there is a God who made us and to whom we owe honor and thanks.

In the 1980s, a number of Protestant philosophers led by Alvin Plantinga, Nicholas Wolterstorff, and William Alston developed a sophisticated defense of Calvin’s notion of the sensus divinitatis. Dubbed the “Reformed epistemologists,” they argued that theistic beliefs can be (and normally should be) properly basic: rationally justified even without empirical evidences or philosophical proofs. On this view, believing that God exists is comparable to believing that the world of our experience really exists; it’s entirely rational, even if we can’t philosophically demonstrate it. Indeed, it would be quite dysfunctional to believe otherwise.

Arguments Against the Existence of God

Even granting that there is a universal natural knowledge of God, there are unquestionably people who deny God’s existence and offer arguments in their defense. Some have attempted to exposed contradictions within the concept of God (e.g., between omniscience and divine freedom) thereby likening God to a “square circle” whose existence is logically impossible. At most such arguments only rule out certain conceptions of God, conceptions that are often at odds with the biblical view of God in any case.

A less ambitious approach is to place the burden of proof on the theist: in the absence of good arguments for God’s existence, one ought to adopt the “default” position of atheism (or at least agnosticism). This stance is hard to maintain given the many impressive theistic arguments championed by Christian philosophers today, not to mention the Reformed epistemologists’ argument that belief in God is properly basic.

The most popular atheistic argument is undoubtedly the argument from evil. The strong version of the argument maintains that the existence of evil is logically incompatible with the existence of an all-good, all-powerful God. The more modest version contends that particularly horrifying and seemingly gratuitous instances of evil, such as the Holocaust, provide strong evidence against God’s existence. The problem of evil has invited various theodicies: attempts to explain how God can be morally justified in permitting the evils we encounter in the world. While such explanations can be useful, they aren’t strictly necessary for rebutting the argument from evil. It is enough to point out that given the complexities of the world and the considerable limitations of human knowledge, we are in no position to conclude that God couldn’t have morally justifying reasons for allowing the evils we observe. Indeed, if we already have grounds for believing in God, we can reasonably conclude that God must have such reasons, whether or not we can discern them.