One of the first times I had my faith directly challenged was in ninth grade. I was having a conversation with a kid named Justin who sat next to me in pre-algebra. Somehow the subject of church came up, and when he realized I was a Christian he cocked his head and asked, “You believe in god?”

“Of course I do.”

He laughed. “Why do you believe in god?”

I was a little flustered. How could anyone not believe in God? “Well, it’s the only explanation for how the universe got here.”

“But that’s what they used to say about everything.”

“Huh?”

“People used to not understand things like lightning and earthquakes, so they invented gods to explain them. That’s why they used to worship the god of lightning or the god of earth. People who worship the Christian god are doing the same thing.”

I had never heard this argument before so I was pretty disconcerted. Was it possible that Christians were just as foolish as the people who worshiped Greek and Roman gods? This conversation planted a seed of doubt in my mind, but I buried it away and didn’t think about it again for years.

There was a time when people assumed rainbows must have been created by one or more gods. And who could blame them? Rainbows form a perfect semicircle and the colors line up in the same order every time: red, orange, yellow, green, blue, indigo, and violet. How could anyone not think rainbows were designed? And if they were designed, then it followed that they were some sort of message. Perhaps a covenant of some sort. Of course, now we understand that rainbows don’t need a designer. They occur naturally when light is refracted through drops of water and broken up into its characteristic colors.

That’s not the only supernatural explanation that was later replaced with a scientific one. People used to believe earthquakes and lightning occurred when the gods were angry; now we know about plate tectonics and electricity. People used to believe lights in the sky were spirits; now we know about the Aurora Borealis. People used to believe sickness was caused by demons; now we know about germs. Similar things could be said about rain, eclipses, stars, and so forth.

There have been thousands of times throughout history when people used god or some other supernatural idea to explain things. And people still do it today. For example, since no one knows exactly how life came into being in the first place, many people say god created life. And since no one knows exactly how the universe came into existence, many people say god created the universe. But just because scientists don’t understand something doesn’t mean they should throw up their arms and declare, “God did it!” If they did that, they would be no better than the primitive people who said the same thing about rainbows.

There are many things scientists still don’t fully understand (black holes, dark matter, quantum mechanics, etc.), but they keep looking for answers because mysteries have always turned out to have a scientific explanation. Always. The reverse, on the other hand, has never been true. Just try to think of one scientific theory that was later replaced with a supernatural explanation. The reason you can’t is because it has never happened. This is one of the many reasons I don’t believe in god.

My ninth-grade classmate was right. People have always invented gods to explain natural phenomena, and today they’re still doing it. The only difference is that today there’s only one god left (at least in most of the Western world).

If someone provides evidence that god exists, I will gladly consider it. But I’m going to need something better than, “You can’t explain this, therefore god.” If you’re a theist, you can cling to every scientific mystery as evidence that god exists, but be prepared to see that evidence debunked. As Neil deGrasse Tyson said, “If that’s how you want to invoke your evidence for god, then god is an ever-receding pocket of scientific ignorance.” Put another way, god is getting smaller. Someday he might disappear completely.