My 2nd grade religious education teacher couldn’t give satisfactory answers to me questions and I was sent from class when I argued, I realised if questions were a problem I wanted nothing to do with it.
I was 13; it happened during my Bar Mitzvah service.
I started doubting seriously when I was fourteen, and went through years of “it’s true, it’s not”, praying, begging for miracles, etc. I was around twenty or so when I was sitting in the library at college and was reading something relevant and suddenly it came to me - not only did I not believe, but that was ok, too. I didn’t need to believe.
I do have memories of believing in God or Gods, but I also have memory of believing in the Tooth Fairy and Santa Claus too, so I don’t really give that much weight.
I’d say I was somewhere near puberty when it all came together for me and I figured out what’s what.
I don’t remember ever having any kind of strong belief, but because I attended a parochial school and have very deeply religious parents, I went through the motions. I must have been in my early teens when I finally articulated to myself “this is all bullshit.”
The first time I prayed for salvation I was about age five, and I clearly remember hoping that it would be good enough to keep me from going to hell, because I knew I wasn’t feeling the things I was supposed to be feeling. I went to a private Christian school until sixth grade, so throughout my childhood I was getting plenty of religion and having a lot of guilt and fear about it.
As I got older, I read about different religions, but I never found the one that clicked. And one day I finally realized that I was searching for something that was never missing in the first place! At that moment, I felt relief and joy and understanding…all the things I had failed to find in church.
My disbelief had been simmering below the surface most of my life. I secretly rejected my religion shortly before I turned 31, and discovered several months later that without my old religion I was atheist.
Took a while for me. I remember as a kid, around age 6 or 7, reciting all the usual stuff in church and thinking, “Does saying the same stuff over and over every week really make God happy?” I’m pretty sure that was the first seed, but it lay dormant for years while I attended a Catholic high school.
Then I took a philosophy class in college and realized that basically, the universe as it exists just doesn’t fit with the idea of God that everyone seems to have. The dominoes fell pretty quickly after that.
Do you mean that you never believed at all and realized it at that moment, or that you had accepted the opinion of your parents (or whoever was taking you to church) until that moment but then realized they were wrong?
I used to detest being dragged to church every Sunday, since I never really believed, and saw the whole process as a colossal waste of time. Many times I tried using logic with my mother in an attempt to get out of going. Once I flat out asked her: “if ‘God’ knows my heart, and knows I love him, why should I have to go to church and prove it?”
You can guess her answer: “Because I said so.” 
I believed in god or gods for a while because I was raised that way. However, my parents were never that religious, going to church or a Buddhist temple mainly for the socializing. Whenever they’d talk about religion, it was to cite Buddha or Jesus or “god” to teach me a lesson about something, so I never had much formal training
As I went through high school, I spoke to more and more people about religion. I realized without specifically thinking about it that I was taking the atheist position in all of my arguments, and that I believed it. It was then that I consciously made the change from weak religionist to hard atheism. I would require proof for things, real proof, and if that cannot be provided, then reason and logic would do. Once I realized that you could plug in any name or gods for a specific religion’s argument, I realized that they were all fake
I’m not QUITE atheist, more like halfway agnostic with a side of Zen Buddhism (I do it for the meditation, not the theology).
Regardless, I had a relatively strong faith in God in my youth, but around Confirmation time I started feeling less and less like I had any faith. I still had something akin to “belief”, but like some posters above I felt like I was forcing it–and what’s worse, no one could answer the questions that I had about the whole situation.
Presumably the right priest with the right knowledge of theology and ability to deal with a surly, bookworm teenager could have prevented it, but meh. I went through the motions of Catholicism until my first year of college, when I started realizing that I COULD just stop going to church, and no one was going to make me go. And realizing that I didn’t see any point to going if I wasn’t being forced was what really started me on the final slide out of there–as far as I could tell, I didn’t need their help to tell me to be good, much of what they claimed was bad was neutral or good (like homosexuality, and eating meat on Fridays in Lent, and any number of other things.).
My mom still honestly believes that I’ll have a Saul-on-Damascus-Road moment and come back. I’m not holding my breath.
I said between 10 and 13 though I’m not sure the exact age. It was more of a slow, dawning realization, but I know by the time I hit 13, I didn’t believe, and I’m pretty sure when I was under ten, I took it for granted that of course there was a god.
I was never brought up religious. It was just something I assumed without really reflecting on it.
I had sort of the contrary argument. If God existed and was as described as our church, He certainly knew that I didn’t believe in his existence, and further he knew that I felt that, if he DID exist, he had a whole lot of 'splaining to do about, for instance, the Amalekites. (Mentioned because it was that particular story that caused the scales to fall from my eyes about Yahweh being beneficient.) Given that, not only was God not going to be impressed by my going to church and professing salvation, but in fact I was just buying myself a ticket to an even worse neighborhood in Hell.
I felt that the idea of going to hell was a compelling enough possibility that I should give believing in god the old college try, but I don’t think I ever really managed it. That was a long time ago, though, so maybe I actually did believe for a while. By high school I was over it, though.
I don’t remember very clearly exactly what I believed, but I guess I just took my parents (actually, it was a grandmother who pushed it the most) at their word until I started going to church and figuring out that Jesus never showed up, that God never answered prayers or showed his existence at all, and none of the miracles they talked about ever really happened.
My beliefs in a nutshell: I don’t believe in a soul, or in an afterlife, or in any other supernatural phenomenon. I believe that there is no omnipresent power or entity with domain over humanity, only that we own our own fate and are responsible for our own actions.
I had believed in God and Jesus and all the Christian trappings through childhood, but my faith began to waver when I was 13.
My step-dad at the time took me to an Assembly of God church, and while it wasn’t a particularly holy-roller type of congregation, the hymns very much revolved around “stay righteous and crush the enemy”-type exhortations, while the pastor had a “peace and love” vibe. This set up a kind of cognitive dissonance that persisted for a few years - I wasn’t ready to absolve myself of religion, but I was uneasy about the contradictions that I began to notice popping up all over as I read the Bible.
Through high school and into my early twentiers, I gradually lost any Christian faith, replacing it with various vague New-Agey beliefs involving reincarnation and watered down Buddhism (basically whatever crap I thought up whilst getting high with my homies). Eventually I settled into an uneasy agnosticism, where I rejected organized religion, but also wasn’t confident enough to espouse a godless worldview (the whole blissful afterlife thing is a bitch to give up, kind of like smoking).
Sometime in my thirties, I gradually developed a worldview something like metaphysical naturalism - the belief that only natural laws inform and describe the world around us. And paralleling this process, it also became clear to me through much consideration,study, and observation, that the holy texts and scriptures of most, if not all, religions are by and large collections of variously authored and translated works, of mostly fictional or at best anecdotal origin, and have been embraced by the masses out of an anthropological need for a common moral and social framework.