Theists do not understand that. If you get into a discussion about religion, they think you went to university to study atheism.
You decided you hated Jesus at 15 because you wanted to have sex and smoke pot, so you decided to study Dawkins and Hitchens for your undergraduate with a view to doing an MA in Evolution.
The vast majority of atheists I know and have spoken to just came to reject the claims of their religion, that's it. Many including me were not happy with the label and it's connotations.
I thought an atheist was a communist when I was a kid, communists being bad because they are Russian!
"I suppose this means I am an atheist," was my conclusion after finally rejecting it all.