Atheists, how old were you when you came to the realization that there is no god?

My parents arent religious but we celebrate santa clause so i never really thought about it until i was 13 when kids at school brought it up and asked me i didnt even know what an atheist was until they told me i was one and said i was going to hell. It was a rude awakening so i talked to my parents and decided that i was agnostic ( for the sake of my friends) it wasnt till i was 17 that i started telling everyone that i am an atheist but i guess ive been one all along i just didnt know what to call it