Third grade. It was at the same time I figured out Santa Claus wasn’t real. I basically applied my reasoning about Santa to God and decided they both were make-believe.
Somewhere between 2nd and 5th grade. It’s hard for me to date memories from when I was that young- they all sort of melt together. But I was in a school van taking a trip to the city library when some of my classmates were having a discussion about religion. I discovered one of them didn’t believe in God and the idea of that just hit me like a ton of bricks. I never knew there was an alternative to believing in God. That wasn’t really when I decided in my head that God couldn’t exist, but it certainly set me down the path.
My oldest memories of religion/god are from when I was 4 or 5 and my mother was forcing me to say my prayers. Even at the time, when she tried to explain who/what god was to me, I thought it was bull. I continued to go to church until I was 11 mostly because my mother had to send me (she promised my father she would when they divorced). I even became an altar girl because I thought it would make my father happy. Once I realized that my father is a douchebag, I stopped pretending to believe in something I had never believed and I stopped going to church altogether.
I never believed. Religion wasn’t taught in our household. Christmas was just a time to see pretty lights and get presents, Hannukah meant visiting family and getting presents, Easter meant chocolate bunnies, Passover was again for visiting family and eating special foods. *God *never entered into any of it. When I was a child, I thought of different religions as no more than belonging to different clubs. Like, you could be in the art club, or a class for gifted students, or the drama club, or a Christian, or a Jew, or the Girl Scouts and you could be in any combination of these things, because being one didn’t mean the exclusion of any others and none of them really mattered because they were just stuff you did. I didn’t really realize that there were actual *beliefs *involved or that some people took them so seriously until quite a while later.
I third the version of sitting in a church during a sermon as a very small boy, not believing anything the priest says, and wondering how the ostensibly sane people around me can honestly believe it, and if they do, how are they different from a lunatic. Faith is still a mystery to me, as my entire family is deeply religious and I’m the lone atheist/apatheist in the bunch.
I don’t know that I ever genuinely believed in god. But my earliest memory on the topic is playing with my action figures when I was 5ish and thinking “I wonder if this is what it’s like to be god?” then laughing for a few minutes. I’ve never been able to take belief in god seriously since.
Pretty much the first time someone I trusted to explain the world to me (probably a parent) tried to explain God. So 3 or so?
I blame Sally Struthers.
I am a baptized Christian (I still have the baptismal certificate) and my family was very religious. Back in the 80’s, Sally Struthers started parading starving black kids on TV and comparing their lives to how much coffee you drink in a month.
The reason that there were so many starving people was the famine in Ethiopia at the time. Logically, the only way God could possibly allow so many people to suffer was that there was no God.
I never believed, but I didn’t realize I didn’t believe until I was in my early to mid teens. Like others, I also had an “oh crap” moment, and a sick, sinking feeling in my stomach when it hit me that people actually believed the stuff we were told in church was real, and an accompanying sadness when admitting my parents were some of those people.
I never believed. My parents were small-l liberal (though voting NDP), and my mother’s parents were old-school European socialists, so we got very little religion of any sort. My mom and her sisters sang in church choirs, but I remember my aunt saying once that the only reason she went to church was for the music.
I was the kid who read science books in kindergarten. Going to Sunday school was a weird experience. I remember the time I formally broke away from religion, though. Around age eleven I’d joined the choir for six weeks as an experiment. I stuck it out for the minimum six weeks, then announced to my mother, “I can’t sing this because I don’t believe it.” She accepted that and we moved on.
I call myself a secular neo-pagan. I like neo-pagan stuff, and feel more comfortable around it than I do many other religions–mostly because of the acknowledgement that people differ and ‘there are many ways to the goal’–but it’s kind of an artistic like. I don’t believe in any of it.
My husband (boyfriend at the time) agreed to go to Missionary discussions and eventually convert to the Mormon church. We went to the stake missionary’s home, sat at his kitchen table, listened to two young men explain the same things I’d been hearing my entire life in church and at home and the past two years in seminary. There was absolutely nothing new about any of it, and I looked Jaime and I thought “I’m not buying any of this” and I knew he couldn’t be either. From there, I didn’t know what to do so I subjected us both to a month of that crap and made him get baptized.
Turns out, he never bought that crap, either. I was sixteen at the time, but it took nearly 3 years before I felt comfortable calling myself an atheist. I didn’t even really understand the word until about a year later when I discovered the SDMB and started reading intelligent posts by self-avowed atheists explaining that yes, it was possible to truly believe there is no God.
Wow, I never really realized how well I was indoctrinated; it took me until I was in college to realize that religious experiences were more likely to be products of people’s mental states than actual divine intervention. Previous to that it’s hard to say I was a believer, and I stopped going to the Youth Group at church in high school soon after I was old enough to drive (or in my case, not drive) myself there. However, I’m not a complete unbeliever, but I am extremely skeptical of everything. I find it rather difficult to believe in the conception of the Catholic god I grew up with, but I can’t completely refute everything that is said about the nature of reality I know nothing about. I find it extremely likely based on available evidence that every religion was founded by either a lunatic or a grifter, and not by someone who received actual revelations from an extremely powerful being that does not leave much evidence of its existence, but I wouldn’t say I don’t believe or believe in a lack of God.
I’m not sure. I suspect I didn’t really believe any of it (including Santa Claus, Easter Bunny, etc)
until one night, due to a juxtaposition of headlights on the wall of my bedroom, I was absolutely convinced the devil was in my room.
And I was really annoyed with all these movies showing the devil showing up, but never the god. And, however it happened, I decided right then and there that if there WAS a god, he was an ass and I didn’t want any part of him.
So, I need to find a term for the belief that “I don’t give a rat’s ass if there is one or not; it doesn’t affect my life one way or another”. 
“Apatheist.”
My parents are atheists, though my Mom won’t admit it. I was raised with no religious instruction at all and never believed in God. I learned about the Bible stories but even at an early age I looked at them the same way I looked at the Greek myths I was also taught. People actually believing in them was something I had a hard time wrapping my head around. I still can’t fathom it.
/thumbsup
I worked in the high school English book room my senior year, and there were a stack of Bibles for the Bible as literature section of senior AP English. I read the intro, where I learned of the multiple authors of the Torah. The scales immediately fell from my eyes.
I voted for the 31-40 year range. But the first hint of realization happened when I was in 7th grade. I distinctly remember, I was sitting in church when I suddenly thought “Hey, I really believe this stuff.” Prior to that, I suppose, it had never occurred to me not to believe. From that point on, my belief was more of a conscious thing that I had to work to maintain. It took years (and piles of guilt over my doubts) before it occurred to me that the whole belief thing was not worth maintaining. That was in my mid-30s. I am much happier now, FWIW.
I was raised Lutheran, and got most of my church time before the age of 12. It was there, nothing too big in my life.
When I was 17, I dated a born again Christian for about 6 months, and embraced it. I really tried to get into it, and went to church 3 times a week. I did reading and thinking and all sorts of things.
Once we broke up, I lost the romantic fervor for the situation, and started really thinking about it. My first big moment was in thinking about the “sin” of masturbation. I felt guilty, and then started analyzing the reasons for it being a sin.
It didn’t take long from there, and by the age of 19, I was a full fledged atheist.
Eleven. It happened overnight, really. I was never a serious believer and had only a vague notion of a god. One day, I realized that I believed in god for no good reason - that there was no though put into it. My belief was based, not on evidence, but on it being the only option I knew of.
Been an atheist ever since.