2010 even though I was never a believer growing up Catholic. That's when I started to call myself an atheist.

I started questioning things in my mid 20s. It was a gradual process at first, but once I opened my eyes to atheism I looked back on things and kinda had a "Wtf why did I ever buy into that crap!?" type of moment.

When I started taking Philosophy at High School, gradual process.

In junior high

When I moved to a new city where I had no friends or family. It was a life-changing reboot that allowed me the freedom to take a serious look at my beliefs and philosophies. Like the internet meme with stick figures that says "I didn't lose my faith - I threw it the fuck away." Yup.

After I finished listening to the audiobook of Sam Harris's The End of Faith.

As soon as I realized that religion is BS, back in high school. I come from a predominantly atheist family. I got brainwashed when we arrived in the US (2nd grade) and the Jewish organization stuck me into Hebrew School. I was just getting over one kind of brainwashing while undergoing culture shock, and thus fell for the 2nd set of brainwashing. By hs, I started observing how many different religions there are in the world and that they are constantly fighting against each other, even within certain variations of their own beliefs (like different types of Christianity). I also noticed all the brutality going on in the world, and was wondering where is that omniscient, omnipotent, omnipresent, and all-loving god. That's when I figured out that there is not god, by the end of 11th grade. I switched hs my sr year, and there people already new me as atheist.

About 15 years ago - I went to an atheist meetup with trepidation, because I had never met another atheist, and I expected weirdos, but instead I met ordinary persons with the exception of two atheists who had us laughing for two hours with their natural comedy. We didn't talk about religion.

I started to go to the Unitarian CHurch when I was 12

It's funny, but I have never believed in the supernatural, but I never really thought of myself as an atheist until I was in my late 20s. It never really mattered what I identified as. Religion didn't play any part in my life. It wasn't until I realized how harmful religion is that I felt the need to distance myself from it.

12. I asked a whole bunch of questions to a vicar that came to the school, and he fumbled over most of them. "How could Noah fit every single species on the ark? It would need to be the size of Africa! And if God wanted everyone dead, why not just kill them himself, he's all powerful? And how come there were miracles, real ones, but aren't any more?" Stuff like that. I got a bunch of "well that's just the way God works" BS and I just thought...nah. It's all crap.

About age 8. i started asking a lot of questions in my United Methodist bible class, and wasn't getting any good answers (think Sheldon from The Big Bang Theory on a theoretical roll) ! It was pretty much an instantaneous process. Then, I continued my education, and became widely read, and traveled, and still wasn't getting good answers. That's because there are none. Many people's beliefs are based on fables - the end.

6th grade so about 11 years old. I grew up in the bible belt where you're looked at in disgust if you're not Christian. When I got old enough I didn't care and started questioning religion.

Early 20s, I guess. I never really called myself anything for a long time after I stopped believing in my religious upbringing, but at some point I identified as an agnostic atheist.

Thanks to God for the blessing of loosing faith in him gradually since I was a lamb hanging around, and then he set me free the day I became a holy bull

College

I was in 6 grade, I was extremely bullied by my fellow Christians students. Guess fairy tails just never set in for me.

Around the age of 12 or so.

My whole life. The whole concept of God never made any sense to me. I couldn't see any difference between bible stories and Hans Christian Anderson fairytales.

A decade ago, I never thought I would be.
A 23 on the verge of spontaneous combustion. Woe-is-me

I'm 33 now.... Stopped believing at 23. How appropriate.

Pardon me....

Aged ten. Believe! Believe! Trust! Believe!

When I was about 15. I have grown up in a country where religion has more importance than humanity and over the years seeing all the rituals and fanatic sects and tons of contradictions between various religions despite all of them claiming that there is one god. So I chose to put my belief in me, being a good human, keeping my conscious clean, and doing what feels right.

Right after I started being able to understand geologic time. For a long time I couldn't fathom the time scales. Once I could... The walls fell

Gradual process, it was an accumulation of varying facts that brought me to the conclusion. It happen probably around Junior year of college.

Edit: wrong schooling

I was raised in a christhian home, read the hole bible when i was a kid, but for me it was Music (Heavy Metal) that gave me the confidence to begin questioning stuff and not to be afraid of the consequences of freethinking.
A friend of mine gave me this Iron Maiden album at age 14, and i was afraid of listening the song "The Number of the Beast", because i could be sent to hell, so i just skipped it every time hahaha. But i really liked the music, so eventually i lost my fear and started questioning everything, and when you do that, then you realize that just... there is no god!