At 15 I no longer believed in God, but almost everything else in my life remained the same.

No one knew and there was no one I could tell. I still went to church because my parents made me. The sun rose and set. My shaggy dog continued to greet me at the gate when I came home. My brother continued to joke and tease. But I was restless. My world and my perspective had been flipped upside down.

I wanted to change something on the outside to reflect the changes within. So for the tenth grade I transferred from my strict religious school to a public school, which was considered a hothouse of iniquity by the school I was leaving behind.

I no longer cared what my religious school thought. I had read the Bible through, taken religion seriously, thinking it was the meaning of life. It had disappointed me, fueled my depression, and confused me. Shedding my faith had ended a nightmarish three year depression and replaced it with uncertainty, leaving me feeling excited, alone, adrift, and strangely hopeful.

I also had regrets. I believed I had tragically wasted my whole life. It went beyond years of prayers wasted on a probably nonexistent deity. I had watched too much television, fretted too much over my hair, and spent too much time thinking about boys.

I decided to let go of it all. I would study. Maybe someday I would do something important. I decided I would make an “A” in every subject. I would study each subject until I knew it well enough to teach it. I was a little worried though. I had always struggled with listening in class due to poor concentration.

I decided that this time I would ask the teachers questions after class if I had to, even if I felt shy and even if I annoyed them so much they hated me. I would sit on the front row and focus as much as my brain allowed.

I was worried about my upcoming biology class though. I had sailed through my previous science classes with rote memorization as a “B” student. None of the teachers at my religious school seemed to expect anyone to understand science, but the grade of “A” was reserved for the enterprising individuals who tried.

I was not one of them. I had always secretly suspected that none of the ponderous scientific terms made any sense, and that people only pretended to understand them. Now I was willing to reconsider.

On the first day of my biology class I sat on the front row, tense in my chair. My teacher instructed everyone to open their textbooks. When I opened mine to the first page I saw a definition that on the surface seemed like nothing special. “Biology is the study of life.” They were simple words but I stared at them and could not look away. The study of life.

Why would anyone study life? And an answer came to me: I no longer knew what life was or what it meant. If God had not created it, what had? What was life? Where did it come from?

I looked for answers in the reading assignments. Nowhere in the pages of my textbook was there any mention of a soul or the infallibility of the Bible. Instead, it said that living creatures were made of cells.

I knew something about cells. My textbook at my Christian school had mentioned them, but there they had seemed like nothing more than mechanical explanations for what God had created, a peek beneath the hood of a cosmic car. Now they seemed like a mystery.

I soon learned that science had a way of dealing with mysteries, one that did not require unconditional belief: the scientific method. The scientific method was everything faith was not. It encouraged rather than forbade doubts. Instead of being in competition with observable reality, it sought to discover the universe as it was, not how people wanted it to be.

During the next few weeks, I heard an echo of it in a word I had never heard used at my religious school: critical thinking. For the first time I had a few teachers who encouraged students to question and challenge them. Since I was already questioning everything, I was a fan of this teaching method. But I was also stunned. Being encouraged to think critically was like being given official permission to rebel.

At my previous school rebellion against authority, especially God, was considered the ultimate sin. Certain thoughts, especially religious doubt, were forbidden. It was hard for me to see how students could sit at their desks and look bored while hearing that any idea could be challenged. It was like ignoring an earthquake.

While fascinating, the class was demanding. The teacher taught from the book and gave standardized tests, which most of the class failed. Memorizing was not enough and I made a poor grade on the first test.

After that I asked questions and looked up any terms I did not understand. When a new chapter was assigned, I found myself looking forward to reading it. I soon became thrilled that I was understanding photosynthesis, mitosis, and genetics, and I was constantly seeking personal frames of reference.

My imagination became engaged. Mitosis, a form of cell division, mattered because without it I would not be alive to study it. The theory of evolution, which I had been taught to hate, provided an explanation of life that replaced the creationist view I had lost.

Biology filled the void that religion had left behind, and I read it with the same reverence with which I had once read the Bible.

Most of the students and even the teacher were Christians and never seemed to see anything subversive about biology. I cannot imagine that anyone else in my class experienced biology the way I did that year.

That is because I had entered it feeling like an alien who had been dropped on a strange planet with no explanation of how I had gotten there. And though I had signed up for biology only because it was required, it became ground zero for my quest to understand the world as it really was.

I became the most interested and attentive student in the class. I went to after-school teacher-led study sessions even of I already understood the material. I read and reread and paraphrased every paragraph in my textbook. I even did some reading on my own. I began to break curves. My teacher loved me.

Aside from appreciating the “answers” science gave, I was enjoying the experience of being in an environment where uncertainty was allowed to exist, and where there was no rush to fill the most basic questions of existence with rigid answers.

Science represented a mindset of openness that the absence of my belief had made possible. The question “why,” which I had lost in childhood, had returned. Science encouraged asking why, doubting, and discerning. And because biology encompassed everything alive, once it began to matter to me, everything else did too.

My interest in biology seemed to expand outward to include the whole universe. I liked to imagine concentric circles radiating from my single point of view, up and past the stratosphere, sweeping past Pluto and beyond, and onto the edge of the known universe and back again.

I played with the idea of getting a Ph.D in biology though I never did. But I remember my tenth grade biology intro class with a kind of longing. I remember it as a time when I relearned how to be mystified.

Some accuse science of stripping the world of “magic,” but nothing could be more wrong. The surest way to remove mystery and wonder from the world is remove the power to doubt.

Studying tenth grade biology was more powerful, more ineffable, and even more “spiritual” than anything I had ever read in the Bible. This was true not just because of its answers but because of the questions it permitted asking.

And if I had continued to hold onto my religious beliefs, I would have never known that because I never would have cared.