Christian Worldview: How Do We Know That God Exists?

How do we know things? For example, how do you know which flavor of ice cream tastes best? You sample some different flavors and identify the one that is most pleasing. (Which is bound to be chocolate chip, of course.) That kind of knowing by personal experience is pretty basic.

Then there is knowing that doesn’t involve sampling but involves observation. For example, when you were in middle school how did you know that the pretty red-headed girl across the room liked you? You didn’t dare ask, so you observed things: Did she look at you and smile? Did she find opportunities to talk to you after class? As you observed her actions — or lack of them — you determined the likelihood that she might like you. (Only then did you move to the note-passing stage!)

That famous fictional detective Sherlock Holmes used the power of observation to solve crimes, but he used it in conjunction with another tool — deduction. If he observed a specific residue of sand at the scene of the crime, he might deduce that the criminal had recently been in a certain part of the countryside where that kind of sand was to be found. In other words, he observed the situation, and then made logical deductions from those observations.

Then there is a kind of knowing that isn’t based on sampling or observation but on sheer mental gymnastics — knowing based on logical thinking. For example, the French philosopher Descartes offered the famous notion: “I think, therefore I am.” He argued that even if you doubted all else, the fact that you are capable of thought is a logical proof that you exist.

But what about God? How can we know God exists?

For most of human history, the reality of a divine being seemed self-evident. But we have long since entered the modern era, with its insistence on empirical evidence, and now the postmodern era, in which the very idea that we can know something with certainty is suspect. So where does that leave us with the question of God’s existence?

Many great thinkers have offered “proofs” of God’s existence, and those arguments have taken many different approaches. Some are stronger than others, but taken together they can provide a strong foundation. Taking our three ways of knowing in reverse order, let’s begin with arguments for God’s existence based simply on reasoning.

Perhaps the most famous of these purely philosophical arguments for God’s existence is the ontological argument, first posited by the 11th century theologian Anselm of Canterbury. A summary of his argument is:

— Our understanding of God is a being of which no greater can be conceived.
— The idea of God exists in the mind.
— A being which exists both in the mind and in reality is greater than a being that exists only in the mind.
— If God only exists in the mind, then we can conceive of a greater being — that which exists in reality.
— We cannot be imagining something that is greater than God.
— Therefore, God exists.

Such arguments offer fodder for intellectual debate, but they don’t provide the kind of assurance that many believers would seek. For that, we can turn to arguments from observation, and the most famous of those would be the argument from design.

The design argument is rooted in our observation of a world that appears to have at its core a plan, a design. We look at the universe, we look at the laws of nature, we consider the precise structure that allows life to exist on our planet, and we deduce from that observation that there must have been some design to creation — and design necessitates a designer.

Theologian Peter Kreeft offers this summary of the argument from design:

— The universe displays a staggering amount of intelligibility, both within the things we observe and in the way these things relate to others outside themselves. That is to say: the way they exist and coexist display an intricately beautiful order and regularity that can fill even the most casual observer with wonder. It is the norm in nature for many different beings to work together to produce the same valuable end — for example, the organs in the body work for our life and health.
— Either this intelligible order is the product of chance or of intelligent design.
— Not chance.
— Therefore the universe is the product of intelligent design.
— Design comes only from a mind, a designer.
— Therefore the universe is the product of an intelligent Designer.

Of course, the non-theist — typically an advocate of Darwinian evolution — will argue that the argument breaks down at point 3: They argue that the universe and life itself were, in fact, the product of chance. But this puts a significant burden on the non-theist, because now they must come up with what Kreeft calls “a credible alternative to design.” And here is where the work done by scientists in the Intelligent Design movement — such as Michael Behe — proves so helpful. For example, Behe has demonstrated convincingly that some biochemical organisms are too complex to have evolved slowly, part by part — they are “irreducibly complex,” meaning they simply don’t function unless fully developed. (See his book, “Darwin’s Black Box.”)

Then there is that first approach to knowing: knowing by personal experience. I believe that is the only way that you and I can know with certainty that God exists. In Psalm 34:8, the psalmist writes: “Taste and see that the Lord is good.” Ultimately, it is only through trusting in Christ and receiving Him as Savior and Lord that we receive full confirmation of God’s existence, because we have felt His love, experienced His grace, and received the presence of the Holy Spirit in our lives.

How do we know God exists? Because, as the words of the old gospel song testify, “He lives within my heart.”

— Michael Duduit is dean of the College of Christian Studies and Clamp Divinity School of Anderson University, and executive editor of Preaching magazine.