Atheism’s central conceit is that it is a worldview grounded in logic and scientific evidence. That it has nothing to do with faith, which it associates with weakness. In reality, faith is central to atheism, logic and even science.

I became an atheist early in life and long believed that my fellow nonbelievers were an enlightened bunch. I relished citing studies appearing to show that atheists have higher IQs than believers. But when I was studying for my doctorate in physics, math and astronomy, I began questioning my secular...

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Atheism’s central conceit is that it is a worldview grounded in logic and scientific evidence. That it has nothing to do with faith, which it associates with weakness. In reality, faith is central to atheism, logic and even science.

I became an atheist early in life and long believed that my fellow nonbelievers were an enlightened bunch. I relished citing studies appearing to show that atheists have higher IQs than believers. But when I was studying for my doctorate in physics, math and astronomy, I began questioning my secular worldview.

Like one of Hermann Hesse’s tormented intellectuals, I set off to explore alternatives—beginning with Hinduism, Buddhism and Judaism. This turned into a decades-long intellectual-spiritual journey. Ultimately I became a Christian, but along the way I discovered fascinating differences and similarities among humanity’s many religions and philosophies. I learned that all views of the world differ in three essential ways.

First, foundation. All worldviews are built on core beliefs that cannot be proved. Axioms from which everything else about a person’s perception of reality is derived. They must be accepted on faith.

Even reason itself—the vaunted foundation of atheism—depends on faith. Every logical argument begins with premises that are assumed to be true. Euclid’s geometry, the epitome of logical reasoning, is based on no fewer than 33 axiomatic, unprovable articles of faith.

Second, size. Every worldview—that is, every person’s bubble of reality—has a certain diameter. That of atheism is relatively small, because it encompasses only physical reality. It has no room for other realities. Even humanity’s unique spirituality and creativity—all our emotions, including love—are reduced to mere chemistry.

Third, deity. Without exception, every worldview is ruled over by a god or gods. It’s the who or what that occupies its center stage. Everything in a person’s life revolves around this.

When I was an atheist, a scientific monk sleeping three hours a day and spending the rest of my time immersed in studying the universe, my worldview rested on the core axiom that seeing is believing. When I learned that 95% of the cosmos is invisible, consisting of “dark matter” and “dark energy,” names for things we don’t understand, that core assumption became untenable. As a scientist, I had to believe in a universe I mostly could not see. My core axiom became “believing is seeing.” Because what we hold to be true dictates how we understand everything—ourselves, others and our mostly invisible universe, including its origin. Faith precedes knowledge, not the other way around.

Atheism demands a small cosmos, so that is all secularist-materialists see. They bend over backward to interpret every pixel of evidence solely in terms of space, time, matter and energy. For them, that’s all there is. It’s a religious conviction they cannot prove but take on faith.

Atheists commonly believe that science will ultimately demystify everything. But science’s worldview is becoming more mystical, not less. Witness supernatural-like concepts such as virtual particles, imaginary time and quantum entanglement. Even atheist Sam Harris admits: “I don’t know if our universe is, as JBS Haldane said, ‘not only stranger than we suppose, but stranger than we can suppose.’ But I am sure that it is stranger than we, as ‘atheists,’ tend to represent while advocating atheism.”

The overwhelming evidence, I’ve discovered, makes it crystal clear: Faith is the foundation of the entire human experience—the basis of both science and religion. Our faith in physical reality drives us to seek treatments for deadly diseases like Covid-19, to explore the depths of the sea, to invent the perfect source of energy. Our faith in spiritual reality drives us to create breathtaking works of art, music, and architecture; to see life as a divine creation, not an accident of nature; to be curious about things that are not of this world.

For all those reasons and more, I’ve come to learn that atheists are greatly mistaken: Faith is anything but a weakness. It is the mightiest power in the universe.

Mr. Guillen is author of “Believing is Seeing: A Physicist Explains How Science Shattered His Atheism and Revealed the Necessity of Faith,” just out from Tyndale Refresh.

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