People who have been raised in Christian homes and attended church all their lives are often caught off guard when someone challenges their beliefs. They find they are unprepared to give an answer to the skeptic who rejects the Bible as God’s authoritative word, and who thinks faith is foolish blind acceptance of irrational ideas.
Christian apologetics—defending the truth of Christianity with reason and evidence—helps equip the believer to carry out the instruction of 1 Peter 3:15: “Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have.” I have written previously on the definition, purposes, and application of Christian apologetics. This is the first in a series of blogs addressing specific faith challenges and how you can respond with objective evidence.
How Can You Prove It?
Skeptics typically challenge the belief that God exists by claiming there is no proof: “I don't see any evidence for God. How can you prove He exists?" Children just beginning to consider the things of God often will sincerely wonder, “How can I believe God is real when I can’t even see Him?” These are both good examples of why we need to be able to give evidence-based reasons for what we believe.
When asked if we can prove God exists, we should be careful to first clarify what is meant by the word 'prove.' If by ‘prove’ the skeptic is asking whether we can demonstrate with 100% certainty that God exists, the answer must be ‘No.’ This should not, however, be cause for alarm or discouragement for the believer. Nothing—including the atheist’s claim that God does not exist—can be proven with 100% certainty. This is an important point you can use to level the playing field for the rest of the conversation.
To illustrate the point, consider the fact you can’t prove with 100% certainty that you weren’t created just 5 minutes ago with the appearance of age and a lifetime of memories implanted in your brain. Even though it's possible this could be the case, you have good reasons based on evidence to believe it isn’t true. There are reliable documents of your birth, eyewitnesses who can testify you have existed longer than 5 minutes, photographic evidence you participated in past events, etc. These pieces of evidence point to your having been born as an infant, and lived the actual number of years that correlates to your current age as the most reasonable explanation for your existence.
Likewise, when we give evidence for God's existence, we do so intending to demonstrate that God is the most reasonable explanation for the evidence. We cannot force anyone to be compelled to believe, but we can offer objective evidence worth considering.
Because no one can see God, it may seem an impossible task to present convincing evidence that He exists. But the fact that God is invisible should not deter us. There are many things we know exist even though we can’t see them—things like gravity and the wind, for example. We know they exist because we see and feel their effects. We feel the wind blow against our skin and observe leaves and branches moving in response to an invisible force. We observe that a pebble released from our hand falls downward and not upward, and that we are kept from randomly floating out into space even though we can’t see the force that that keeps us tethered securely to the earth's surface.
The search for causes is the very foundation of science. (This is a valuable fact to keep in mind when having conversations with those who believe science is the only source of truth.) In the same way we identify gravity and the wind as the cause of the effects they produce, we can point to observable effects of God as evidence for His existence. Even though we can’t prove with 100% certainty that God exists, by reasoning from effect back to cause, we can demonstrate that God is the most reasonable explanation for the way things are in the real world.
This evidence for God is typically presented as an ‘argument’ for God’s existence. In this context, an argument is not a verbal battle between two or more persons. It is a truth claim based on reason and supported by evidence. There are at least 20 such arguments for God’s existence that I am aware of, but I will address separately three of the most commonly used: the Cosmological Argument, the Teleological (Design) Argument, and the Moral Argument.
The Cosmological Argument
When challenged by nonbelievers who reject the Bible and who pride themselves in relying on reason and science, it's especially helpful to present evidence that is supported by both science and reason. The cosmological argument provides this type of evidence.
The word cosmological comes from the Greek word cosmos, which means universe or world. This argument is based on the need for a cause of the universe. The basic structure of the cosmological argument can be simply stated as follows:
Everything that begins to exist must have a cause;*
The universe began to exist;
Therefore, the universe had a cause
We can tease out the two premises and the conclusion to give a fuller picture of how this argument presents good evidence for God. The first premise is verified by what we know from experience: things don't just suddenly appear out of nowhere. If they did, we shouldn't be surprised to see a giraffe suddenly pop into our living room, or to look out a window and see a mountain that wasn't there yesterday. It just doesn't happen.
The second premise was not widely accepted until recently. While it was once believed that the universe always existed in a steady state and therefore didn't need a cause, scientific discoveries in the 20th century confirmed that the universe—time, space, and matter—began to exist at some point in the distant past.
One such discovery was the expansion of the universe, observed by astronomer Edwin Hubble in the 1920s. An expanding universe is evidence that there was a beginning point from which the universe originated. (If you could shift the outward expansion into 'reverse,' the space between any given points in the universe would get smaller and smaller until there was no space left between them.)
In 1965, Arno Penzias and Robert Wilson discovered a cosmic background of microwave radiation, which is residual light and heat from a huge explosion. A couple decades earlier, scientists predicted this radiation would exist if the Big Bang really happened. When this discovery was verified, it ruled out any competing theory that the universe is in an eternal steady state.
Other scientific evidence that supports a beginning of the universe includes the Second Law of Thermodynamics (which shows that if the universe were eternal, it would have run out of energy by now) and Einstein's theory of General Relativity (which verifies that space, time and matter are inter-dependent and cannot exist apart from each other.) For more in-depth explanations of these and other scientific evidence, see the recommended resources below.
A Reasonable Explanation
Since space, time, and matter had a beginning, whatever caused them to exist cannot be made of space, time, or matter. Therefore, we know the cause of the universe must be spaceless, timeless (eternal), and immaterial (not made of matter). The cause must also be uncaused (self-existent), extremely powerful (to create the universe out of nothing), and have a mind/intelligence (to choose to create). The God of the Bible fits every characteristic of this description. Therefore, God is a reasonable explanation for the cause of the universe.
Final Thoughts
Responding to faith challenges with evidence-based answers is helpful for keeping a dialogue open and for helping to break down the skeptic's intellectual obstacles to believing in God and trusting Christ for salvation. It is also helpful for the child who is considering the things of God, or the new believer who wants to share his faith with others more confidently. Even a seasoned Christian will find their faith is strengthened by objective evidence that confirms their beliefs are true.
Coming up next: the Teleological (Design) Argument.
*It's important to note the first premise does not say that everything that exists has a cause. This common misunderstanding leads people to ask the misguided question, Who caused God? The premise states that everything that begins to exist must have a cause. God is transcendent and eternal, without beginning or end. He is the uncaused First Cause.
Recommended resources:
I Don't Have Enough Faith to Be an Atheist - Norman Geisler and Frank Turek
On Guard - William Lane Craig
God's Crime Scene - J. Warner Wallace
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