How Do We Know God Exists?

How Do We Know God Exists?

How Do We Know God Exists?
How Do We Know God Exists?

Only a small fraction of the world’s population question the existence of a deity. In fact, the belief in supernatural beings is a universal ingredient in all human cultures, whether they are highly technical like the United States or primitive like the Australian aborigines. For most people, the issue isn’t whether a God exists but what deity is like. Is God one or many? Personal or impersonal? Good and fair or harsh and capricious? Is He the God of the Judeo-Christian religion or the God of some other religion?

Because there is a small—but extremely vocal—faction who denies there is a God at all, we will focus here on the issue of God’s existence. The nature and character of God will be treated in later chapters.


An atheist is a person who denies the existence of a God. A little reflection, however, reveals that the atheist’s position is indefensible. The only way anyone can prove no God exists is to be a God himself. Let me explain.

The total amount of knowledge any single human possesses is infinitesimal compared to the vastness of the universe and the immeasurable amount of information it contains. A person would have to be omnipresent (present everywhere at once) and omniscient (have all awareness and understanding) in order to have enough information to know that no deity exists. And these are the very attributes that are a part of most concepts of God! Hence, no finite human being can prove God does not exist because God may very well exist beyond one’s comprehension or experience.

Of course, this fact stops few atheists from arguing against the existence of God. Rather than admitting (or even recognizing) the irrationality of their own position, many atheists attempt to remove the rationality of the Christian position. They often put Christians on the defensive by insisting believers in God are obligated to prove He exists, rather than atheists bearing the burden of proving God does not exist. These atheists argue that because they don’t believe in God, because their belief is negative, they don’t have to martial any arguments in their favor. So states George Smith:

Proof is applicable only in the case of a positive belief. To demand proof of the atheist, the religionist must represent atheism as a positive belief requiring substantiation. When the atheist is seen as a person who lacks belief in a god, it becomes clear that he is not obligated to “prove” anything. The atheist qua atheist does not believe anything requiring demonstration; the designation of “atheist” tells us, not what he believes to be true, but what he does not believe to be true. If others wish for him to accept the existence of a god, it is their responsibility to argue for the truth of theism—but the atheist is not similarly required to argue for the truth of atheism.1

Consequently, in the atheism versus Christianity debate, atheists claim that the “burden of proof” is on the Christian.

Although it is generally true that the burden of proof is on the person who asserts something, the atheist is wrong for at least two reasons. First, as we’ll see, Christians have given ample evidence for the existence of the Judeo-Christian God. In light of this, if atheists claim God does not exist, they must be prepared to explain why. When Christians state that God exists and offer evidences to support this claim, they have moved the debate into a new arena—an arena in which atheists must prove that the Christian evidences are erroneous.

Generally, the person who claims that he does not have to defend his position normally does so because he has no evidence to support his view. The fact is, atheists cannot refute Christian evidences for the existence of God. Science writer Isaac Asimov, who signed the Humanist Manifesto II, is being intellectually honest when he states: “Emotionally I am an atheist. I don’t have the evidence to prove that God doesn’t exist, but I so strongly suspect he doesn’t that I don’t want to waste my time.”2

The second reason the atheistic “burden of proof” argument is fallacious is this: Christians have a document (the Bible) that testifies to the existence of God. It is always up to the person contesting a document to prove it is false. In other words, a document is innocent until proven guilty. For example, in court cases involving a will, in order to win a judgment, the person contesting the will has the responsibility to prove the will is bogus. In the debate over the existence of God, Christians have a historical document that reveals God exists. If atheists wish to challenge the existence of God, they must prove this document is spurious. Hence, the burden of proof rests on atheists. They do not have to prove the nonexistence of God, but they do have to disprove the objective evidence offered for His existence. If they can’t, then Christian theism is true and atheism is false.


That the Bible is divine revelation (and thus a true testimony to the existence of God) will be demonstrated in the next chapter. There I’ll show that, by using the same methods of investigation used to determine the authenticity of any ancient document, the Bible is truthful in all areas open to investigation. It is not only philosophically consistent, but its prophetic, historical, geographical, and scientific claims have been verified to be factual. If the Bible is reliable in all areas in which historical and other forms of investigation can be applied, it is logical to assume that, in areas of religious truth (such as God’s existence), it will be equally reliable and truthful. So, based on the objective, verifiable testimony of the Bible, the Judeo-Christian God exists.

Now, just because the Bible is true in testable areas does not automatically make it true in nontestable areas. Arguments for the existence of God do not end with mathematical certainties. They are based on probability evidences, the same kind of evidences relied upon by science, history, and law in their search for truth. If someone rejects the preponderance of evidence supporting God’s existence because it is not absolutely certain, then, to be logically consistent, he must also reject all other truths from the other disciplines that reach no higher than probability conclusions. For example, no one is alive today who witnessed the assassination of Abraham Lincoln. However, we can be certain (though less than absolutely so) that the event occurred because of the vast amount of historical evidence that confirms it. The probability that Lincoln was assassinated is overwhelming. In a similar way, scientific theories are a product of experimentation and observation (evidences). However, there is always the chance that future experiments and observations may disprove an existing theory. Thus scientific theories are the product of probability evidence.

Christians insist that the burden of proof is on the atheist when dealing with the existence of God so she will have to confront Scripture. The testimony of Scripture is the most important and potent weapon in the Christian’s arsenal. Why? Because the Bible offers objective, testable evidence for God’s existence, not just philosophical arguments. Moreover, the Bible does double duty: it brings the atheist face to face with the fact that God exists, and it reveals the true nature of God in the person of Jesus Christ. It’s one thing to prove God exists, but quite another to prove He is the God revealed in the Bible. By arguing for His existence from Scripture, both goals are achieved.

At first blush, this may sound like a presuppositional approach to apologetics, but it isn’t. The atheist doesn’t have to accept the Bible as true apart from any evidence. Rather, we first confront her with the Bible’s authenticity through the use of objective evidences, then we let these facts corroborate the truth-claims of Scripture.

Unfortunately, atheists reject the Bible because they reject the existence of God. So they will not accept the Bible as evidence for God’s existence. For atheists to consider the testimony of Scripture, the Bible usually has to be set aside so they can be met on their own turf. This involves presenting philosophical evidence for God’s existence. And these are supported by historical and empirical (observable) facts. Let’s consider some of these arguments.


It doesn’t take much reflection for us to realize that we exist, and we did not create ourselves. And since that’s true, it’s easy to figure out that something or someone besides ourselves brought us to be. And with a little more reflection, we can also see that the entire universe came to be in one of three possible ways: (1) it created itself; (2) it has always existed, and therefore had no Creator; or (3) it was created by something or someone outside of itself. Let’s take a close look at each option.


The Universe Created Itself

This view can be quickly eliminated because it violates a basic law of logic known as the law of non-contradiction. This law states that a proposition cannot be true and not true at the same time and in the same relationship. For the universe to have created itself, it must have both existed and not existed at the same time. In other words, in order for the universe to have caused itself to be, it could not have existed prior to itself. Yet, in order for it to have created itself, it must have had to have already existed. So, on this view, the universe existed and did not exist at the same time. Sounds too complicated to understand? It does so for a good reason: It amounts to a contradiction. It’s like saying circles are square or bachelors are married. It makes no sense because it’s nonsensical, absurd, contradictory. Nothing can exist prior to itself to bring itself to be. That’s logically absurd, hence impossible.

The Universe Is Eternal

Although this view once had scientific respectability, it has fallen on hard times. Most scientists agree with theists that the universe had a very specific beginning. In recent decades, discoveries in astronomy have provided an abundance of evidence that the universe came into existence abruptly (the big bang theory). This theory is supported by the fact that all the galaxies are moving away from one another at tremendous speeds. By tracing these movements backwards, scientists believe that, at some point in time, a tremendous explosion occurred that ejected all matter outward from a central point of high density compression. This, scientists say, marks the birth of the universe.

Further evidence that the universe had a beginning lies in the fact that it is aging. The second law of thermodynamics, one of the most important laws of physics that has no known exceptions, states that the amount of usable energy in the universe is decreasing due to continuing heat loss. In other words, the universe is running out of usable fuel; it is slowly dying a heat death. If the universe is running down, then there must have been a starting point in which it was wound up with a maximum amount of energy. Again, scientific evidence is in agreement with the Bible that the universe is not eternal.

Another piece of evidence is the principle of contingency, which states that everything in the physical universe is dependent upon something else for its existence. Thus, for the universe itself to exist, there must be a cause for its existence. Logically, the universe cannot be eternal if something else caused it to come to be.

Of course, many theists disagree with modern science on the age of the universe and its originating cause, but theologians and scientists agree that the universe had a beginning—it is not eternal.

For many scientists, this conclusion has come as quite a shock. Robert Jastrow, an internationally known astronomer and founder and director of NASA’s Goddard Institute for Space Studies, has detailed this difficult and surprising search in his book God and the Astronomers. His concluding comments speak volumes:

For the scientist who has lived by his faith in the power of reason, the story ends like a bad dream. He has scaled the mountains of ignorance; he is about to conquer the highest peak; as he pulls himself over the final rock, he is greeted by a band of theologians who have been sitting there for centuries.3

The Universe Was Created by Something or Someone Else

We are now left with the third possibility, which the Bible confirms: Something or someone outside of the universe caused it to come into being. Creation out of nothing is the only plausible explanation for the existence of the universe. If this is so, then we have proved the existence of God in the broadest sense. Only God, a Being who is Himself uncaused, eternal, and all-powerful, could by definition be a Creator.

At this juncture, an objection is often raised: If it makes no sense to argue that the universe brought itself into being out of nothing, then what sense does it make to claim that the universe was created out of nothing? Out of nothing, nothing can come, right? This objection raises a good point, which requires an important clarification.

As I demonstrated, it is logically contradictory to argue that the universe is self-caused. It could not create itself without existing prior to itself, which is impossible. It’s also true that nothing—total nonbeing—can cause something to be. Nothing cannot cause anything because there’s no cause present to create an effect. So where does that leave the Christian view of creation out of nothing?

The Bible affirms that something, namely God, created the universe out of nothing. God didn’t happen upon some matter and energy and fashion the universe out of it. God spoke, and the universe came to be (Gen. 1). There was no preexistent stuff out of which God created the world. Is that contradictory? No. Something (God) caused something else (the universe) to exist. That satisfies the law of causality and doesn’t violate the law of noncontradiction.

Therefore, if this philosophical case for God’s existence is valid and sound, which it is, then there should be empirical (observable) evidence to support it, which there is. We have already seen some of this evidence—the big bang theory, the second law of thermodynamics, and the law of contingency. Now let’s look further.


The only way we can know for sure that God exists is if He reveals Himself. If God wanted to, He could certainly withhold evidence of His presence if He chooses, but we’ve already seen some evidence that He is there. That we can even know this much implies He has revealed this information. It also shows that He has made Himself known in ways we can recognize.

When we search for revelational evidence of God’s existence, we discover He has revealed Himself in two specific ways: general revelation and special revelation.

Special revelation is found in the Bible. Scripture not only confirms God’s existence, but it also includes very specific information about the nature of God. For example, the Bible states that God is holy, eternal, omniscient, omnipresent, omnipotent, and omnibenevolent. It tells us that God is triune—Father, Son, and Holy Spirit. However, because many people reject the Bible, they don’t accept special revelation. Consequently, we will continue to focus on evidence found in general revelation.

General revelation is information about God found outside of the Bible. So it is accessible and understandable by all people at all times throughout history. It is a perpetual or continuous revelation of God. It shows that God exists, and it unveils some of His attributes, but it does not provide all the information the Bible does about God, such as details about His triune nature. General revelation occurs primarily through nature (Rom. 1:20; Ps. 19:1; Acts 14:16–17) and an intuitive moral consciousness God placed in all human beings (Rom. 2:14–15).4 From these sources, several arguments for God’s existence can be developed.5 We’ll focus on three.

The Cosmological Case

The cosmological argument is from cause and effect. It states that because the universe exists, there must be an explanation—a cause—for its existence. And since no effect can be greater than its cause, whatever caused the universe must be greater than the universe itself. That greater cause must be God. He is the first cause.

At this point, skeptics often ask, “Who caused God?” This question must be answered if the cosmological argument is to be valid. So let me explain the argument in more detail.

It is an observable and undeniable fact that every effect has a cause in the physical universe. Nothing in the universe exists that is not contingent (dependent) on something else. A tree’s existence is contingent on seed from another tree. It is also contingent on water, minerals, and sunshine. Rivers need rainfall. In the human realm, every tool serving humanity has a cause for its existence. Someone made it. In a word, nothing in the universe is able to explain its own existence.

Unless a first cause (i.e., God) exists, the universe would have to be eternal because there would be an infinite series of causes and effects that would never lead to a first cause or starting point. But, as we have already seen, the universe is not eternal. Therefore, an infinite series of causes and effects are impossible. At some point there must have been a first cause or nothing subsequent would exist. Moreover, because no contingent being (one whose existence is dependent on another) can cause itself to exist, the first cause must be uncaused or self-existent and thus must transcend the contingent universe. This uncaused, self-existent being would really be the first cause, and all contingent beings would ultimately depend on this cause for their existence.

In short, to explain the existence of a contingent, noneternal universe, there has to be a noncontingent being (Creator) who is absolutely independent of the physical universe. This is the theistic God, and He is identical to the Christian God. According to the Bible, God is self-existent (uncaused—see Exod. 3:14; John 5:26) and eternal (has no beginning and no end—see Deut. 33:27; Rev. 4:10). Thus, He could not have been created. He is not subject to the law of cause and effect in any way. On the other hand, the fact that the universe is subject to the law of cause and effect demands (proves) the existence of God.

The Design Case

Closely related to the cosmological argument is the teleological argument, which centers on the order and design we see in nature. In recent decades, the ecologic crisis has focused our attention on the delicate balance of nature. Everywhere we look, we see interdependence, harmony, order, and purpose. The teleological argument points out that such design and order cannot be the product of random processes and chance. Rather, these characteristics indicate an intelligent being caused them.

By analogy, we easily distinguish an arrowhead lying among countless other pebbles because it obviously had an intelligent creator. When we look at a painting, we know it’s the product of a thoughtful artist. Neither do we see computers as chance accidents of nonintelligent causes. In like manner, the design and order in the universe can only be the result of an intelligent creator, God.

Without realizing it, many atheists acknowledge the concept of an intelligence behind nature when they use the term Mother Nature. It plainly carries the idea of a creator who designed and maintains the natural world.

Now some atheists argue against teleology by claiming that given enough time, the apparent design in the universe could occur by accidental random processes. However, there is no convincing evidence to support this claim, as we’ll see in Chapter 11.

The Moral Case

The cosmological and teleological arguments outlined above represent general revelation in nature. The third evidence for the existence of God also comes from general revelation, but more specifically through human moral consciousness.

The most serious (and common) argument used by atheists to disprove the existence of God is called the problem of evil. In its many forms, it boils down to this: because there is suffering and evil in the world, God must not exist. If He did exist, He would not allow suffering and evil. So either God does not exist, or if He does, He is not the loving, sovereign, all-powerful God described in the Bible. A fuller answer to this argument is found in Chapter 13, but it deserves a short response here.

There is a fundamental contradiction in the claim that evil precludes the existence of God. The moral standard used to determine what evil is can only have its source in God. Hence, by identifying what is evil, atheists implicitly acknowledge that God is. Let me explain.

We could not know what evil is, in any universal sense, unless a moral standard exists outside of us. Without a moral absolute—namely—independent of human consciousness, there would be no criteria to determine what is right or wrong, whether what is wrong today will be wrong tomorrow, whether what is wrong for me is also wrong for you, and whether what is wrong in my culture is also wrong in yours. In short, I could not justify telling you what you ought to do unless there was an absolute standard of moral behavior independent of individual persons and cultures. But such a standard does exist.

Comparative studies in anthropology and sociology reveal a universal standard of behavior in all people, regardless of their culture, religion, or their period in history. Not only Western culture, but also Eastern societies of Hindus and Buddhists and Egyptians have had a similar concept of right and wrong. Even primitive cultures have exhibited this universal awareness of what is evil, this innate sense of right and wrong that helps people everywhere judge the injustice of others and themselves.

This generic moral code is manifested worldwide in prohibitions against murder, stealing, lying, rape, cheating, and so on.6 Interestingly, this moral standard was written in the Bible some thirty-five centuries ago and summarized in the Ten Commandments (Ex. 20:1–17). Although God revealed these commandments to a small culture, living at the time in a foreign land, they were just as applicable to every culture on earth then as they are today. The Ten Commandments represent a worldwide, universal standard for moral behavior.

Since a universal moral code exists, where did it originate? It must have come from a standard outside of man if it is to judge the actions of man. History has consistently shown that when we follow our own standards of behavior, our natural tendency is to do evil, not good. So if morality is relative—if it is determined by whatever culture we happen to reside in or by whatever beliefs we happen to agree with—there would be no worldwide moral continuity. A universal moral code would be nonexistent. The only reasonable and satisfactory explanation for a universal standard of moral behavior is that it is derived from a moral absolute independent of human thoughts and feelings. And this absolute could only be God.

By nature, God is perfect in love, wisdom, goodness, and righteousness. Thus only God is able to judge perfectly what is right and wrong. God’s eternal, unchanging nature guarantees unchanging, universal, and permanent moral standards not subject to human capriciousness. Only God can be considered the source of moral ideals. Therefore even human moral codes point to the existence of God—the moral lawgiver.


We’ve surveyed enough evidence to know that the facts overwhelmingly weigh in favor of the existence of God. But the best proof—the Bible—still remains to be explored. For if God has spoken to us in Scripture, then we can be certain that He is.

This brings us to Jesus Christ—where all apologetics ultimately lead. As Christians, we know God exists because the Bible teaches that He came to earth in the Son, Jesus Christ, and lived among us (John 1:1, 14). Jesus is the “exact representation” of God’s nature (Heb. 1:3, nasv), and in Him “all the fulness of Deity dwells in bodily form” (Col. 2:9, nasv). If one wants to know if God exists and what He is like, all he has to do is read the Bible and there meet Jesus Christ (John 1:18). No further search is necessary. Nor does one have to debate philosophical proofs. God has taken the initiative and revealed Himself to us: in nature, in our moral conscience, in Scripture, and in Jesus Christ.

1 George H. Smith, ATHEISM: THE CASE AGAINST GOD (Buffalo, NY: Prometheus, 1979), 16.

2 Steve Hallman, “Christianity and Humanism: A Study in Contrasts,” AFA JOURNAL (March 1991), 11.

3 Robert Jastrow, GOD AND THE ASTRONOMERS (New York, NY: W. W. Norton & Company, 1978), 116.

4 More is said on general and special revelation in chaps. 9 and 10.

5 Most books giving arguments for God’s existence tend to be very technical, for academic specialists only. But here I will cite five books, each geared for nonspecialists, and each well worth your time. They are listed in their order of difficulty, from the easiest to comprehend to the ones requiring more reflection: William Lane Craig, THE EXISTENCE OF GOD AND THE BEGINNING OF THE UNIVERSE (San Bernardino, CA: Here’s Life, 1979); Norman Geisler and Ron Brooks, WHEN SKEPTICS ASK (Wheaton, IL: Victor, 1990); C. S. Lewis, MERE CHRISTIANITY (New York, NY: Macmillan, 1952); D. Elton Trueblood, PHILOSOPHY OF RELIGION, reprint ed. (Grand Rapids, MI: Baker, 1973); J. P. Moreland and Kai Nielson, DOES GOD EXIST? THE GREAT DEBATE (Nashville, TN: Thomas Nelson, 1990).

6 C. S. Lewis demonstrates this fact in his book THE ABOLITION OF MAN (New York, NY: Macmillan, 1947).

Story, D. (1997). Defending your faith. Originally published: Nashville : T. Nelson, c1992. (19). Grand Rapids, MI: Kregel Publications.

How Do We Know God Exists?

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