I stopped believing in God (at least, a theistic god) about the same time I stopped believing in Santa Claus. I didn't suddenly have an epiphany after meditating under a cherry tree for a year. The cause was closer to home. It started in a book.

For the first few years of my life, I was as Christian as a non-baptized person can get. I attended a Catholic school from the age of four. There, I was taught that God created the world in six days, and that Adam and Eve were the first humans but were cast out of the Garden of Eden for eating forbidden apples. I lived a few doors down from a church, and every once in a while I went to Sunday school to learn about stuff like Noah's ark and Jesus' disciples. I prepared for Communion with my class and drew pictures of what God might look like. At night I'd make my parents read me the story of creation because I liked hearing about how God made all of the animals. I took in everything about religion with unquestioning faith. After all, why would my ­teachers teach me something if it wasn't true?

After four years, I moved to another town and attended a different (non-religious) school. Learning about God was pushed to the back burner as I made new friends and read encyclopedias. Toward the end of elementary school, I borrowed a book about physics from the library (I was, and still am, a giant nerd). It taught me about Newtonian mechanics, relativity, and quantum field theory. It also disproved the existence of Santa Claus. Evidence like gravity and relativity was the straw that broke the camel of faith's back.

After I finished that book, I realized that I didn't believe in Santa Claus. What's more, I saw that I hadn't believed for quite a while. Sure, I'd wanted to believe in Santa, but wanting to believe and believing are very different things.

The same thought process led me to doubt the existence of the god I'd learned so much about as a kid. Before, I'd assumed that God had made the dinosaurs and planets and stars. Now I began to wonder. The Bible said that the Earth was made in six days, and that all of that occurred about 6,000 years ago. But hadn't my teacher told the class that the Earth was four billion years old, and that it had formed millions and millions of years after the sun was created? Gravity seemed to fill in for God nicely in that respect, and these time frames made more sense.

I had another problem. If God existed, why wouldn't everyone worship the same one? ­Instead, the ancient Greeks were pantheistic, and Hinduism, Buddhism, and Shintoism were practiced in Asia. Why would God make himself apparent to only half the globe? It just didn't make sense.

As I grew up and became more interested in science, other stuff I read made my doubts grow. How did evolution fit in with the creation story I'd loved as a kid? Why did God let good people in third-world countries die of starvation, but then reward the bullies at my school with cell phones and iPods? It didn't seem possible to me that the God I had read about in the Bible – who cared about his creation – existed today. This thought made me sad.

I like the idea of having someone watching out for me, and I haven't completely ruled out the existence of a god – but if there is one out there, it's certainly done a good job of hiding itself. The jury isn't out yet. Sometimes, late at night, I'll still say the occasional prayer, just in case anyone's listening.