What.
Nice generalisation. We'll use an example. I was brought up Catholic. At about 12 I started to question this belief system that had been handed to me. I got into my religion thinking maybe if I digged harder, I'd find what it seemed everybody else had.
I didn't. So I questioned it. I felt guilty, I thought 'shit if I make the wrong decision I'm doomed', etcetera. After a few years, and by the time I was 15, I had well and truly decided that I was an atheist, and that everything I had believed in was a dirty sham.
So no, it's not easy. I haven't seen anybody here say it was easy.
But go back to what I just said. If you get enough people saying something is true, and if this lie is perpetuated over enough years, then people begin to think there is no need to prove what they believe. 'How can this many people be wrong'