I think most of us arrive at our anti-god stance the same way we arrive at our anti-unicorn stance. The lack of evidence and reason lead us there. I don't think it's anger that turns people from a belief in a deity.
Being angry at organized religion is not, however, an unreasonable, unjustified position. Organized religion has done, and continues to do, great harm.

Their angry about all the wasted time in church and the Sunday mornings they could have slept in.

I seriously do not think it is any of our job to invalidate their anger. Be the example, sure, and support positively, but allow them to work through it and heal. I was angry as well, but time has mellowed it.

I grew out of my anger as well. Now I find it's stupid and funny.

Can't say I disagree with you. There are too many athiests out there who would burn down every church, temple and synagogue on the planet and impail all their members until dead if they thought they could get away with it. Which as far as I'm concerned makes them no better than militant christians who blow up abortion clinics and shoot up night clubs, schools and church's.

I think allowing them to vent to understanding people and poeple who have had similar experiences is the only thing we can do. Eventually... hopefully... this will allow them to get it out of their system for the most part. Although I doubt they will ever be free of it, I do think that anger will be greatly diminished and usually only surface when the subject arises.

I think anger is a partly a response due the fact that one feels lied to if they have come from a religious background

Live and let live my brother. Time to heal will help them. Hearing others on this forum will say what they already feel and they want have to say what's on their minds.... my opinion my brother.