I am an atheist probably since I was 10. I guess it was an inevitable gradual process that comes to be by learning about science and plain old common sense.
A few events I remember that shaped my skeptic mind went on like this:
While learning about the origin of the Universe in the 4th grade, a teacher made the ridiculous mistake of putting in the same level the Big Bang, the Steady State, and none other than the “God done it” hypothesis. I was 9 but even then I knew one definitely didn’t belong there. And while there already was definitive evidence for the Big Bang and the Steady State was long gone, the teacher didn’t seem to know this – nor did she know the answer to my sincere but apparently unconfortable question – If God made it, then who made God?. She was religious as most people in Colombia are (we used to be officially catholic until 1991) and she brought her ideas into the classroom despite them not being on the textbook. Unfortunately I was the only one taken aback by this.
Anyway, she didn’t like me very much and was constantly bothering me about my long hair.
Another thing that happened was realising how much in common the local indigenous myths and other folk tales had with this other story everyone- including myself – seemed to take more seriously. Everybody was just obviously making stuff up to explain what they didn’t or couldn’t know. Once I learned about this and about the other myths and legends from everywhere around the world I asked myself “What if we were colonised by the chinese or some other culture?.
It became evident that any people will create and postulate what they need in order to make sense of what they can’t undestand. In that moment I knew that religions must all be man made.
Finally, I learned about Evolution and really understood what it meant for our supposed “special place in the cosmos”. My biology teacher insisted that while it’s true that we’ve evolved, we are somehow appart from the rest of all species. I knew this was rubbish, I’m an ape and so are you – deal with it.
Somehow feeling at the same level than a snake, a gorilla, a fish, or all those bugs that creeped the hell out of me back then, made me realise how incredibly fortunate I was to exist along them, and have the joy of sharing this precious time in this incredible world with the company of my family and friends, and to not waste my time with superstitious nonsense.
This, among many other things, is what lead me to the conclusion that reality is all there is and matters, so learn and appreciate all you can about it. And that’s why I’m an Atheist.
…and also not an astrologer, not a witchcraftist, a vicious antihomeopath, also not a ufologist, well… you get the point.