Believe it or not, I read this entire thread in the last two hours. So, a few things:
Why many atheists do not think of atheism as a religion is because they associate the word religion with many negative aspects or actions. In the same way that Christians would not like to be labled 'Extremists', because (here in USA anyhow), 'Extremists' evokes many negative thoughts and images.
2nd, I dont consider myself atheist or agnostic or anything, because labels only serve to divide us and set up us versus them mentalities. However, I can say that I do not believe in the Christian god, nor any all-knowing being that created the universe, etc.
I think that other people who want to believe in that should have every right to do so, as long as they are not trying to push that belief on others. Personally I think religion has held the world back for years, has caused more deaths and evils in this world than any other single entity.
As far as the 'thinking inside a box' line of thought, that it was modern education is all about. We start with what we know, and then we study, research, and test our ideas to prove them. If we start off with no box (i.e. anything is possible) then there really is no point in trying to prove anything, or truly learning at all.
As an ending, if atheists or non-religious persons seem to be bitter, or sometimes laugh at you like they think you are crazy, or patronize you for your religious beliefs, just remember that while that behavior really is rude, we have to constantly put up with that same behavior day in and day out. We are constantly bombarded with religious messages that irk our senses.
I think we should all be able to accept one another's view points, religious or not. I think once we cross over from friendly discussion to implementing religious rules into law is when we need to take a step back and do a reality check. Religion (or lack thereof) really should be something that is kept at home or used as a personal compass, not something that we build organizations around or governments around.
Peace to you all.
Adam