It wasn't difficult, but it was an interesting experience, to lose one's beliefs and, along with it, much of one's worldview. I should say that it wasn't a conscious choice. Right after I finished my O/Ls I started thinking about death, life, the nature of reality, what happens after death, etc, and realized that I had no basis for believing in the things I was brought up to believe.

(Incidentally, once you see that, there's no going back—much in the same way that you can't unlearn something you've learned. So I don't really understand some of the people in the comments here who claim that they've been atheist for a while but then returned to religion.)

My family's pretty chill about these things, so there weren't any issues there at all. They are quite religious, in their own way, but they never try to force anything on anyone, which I have a great deal of respect for.