I agree with Wolfwood in that religion is a means of having power over others, but I do not think it is merely that simple. In my opinion, religion is also a hierarchy of hypocrisy layer upon layer of which was created to shore up the insecurities of the scared and desperately alone.
At its foundation, religion is basically good. However, what I mean by foundation is that which came before its creation; the flickers of insight and imagination had by a man that others after him wanted to attain. This good is desired by those too scared to think for themselves and develops into the worship of a man. So rather than searching for oneself, the devout worship the son of an infallible being and praise him as their lord -- something no one can hope to attain. This, I believe, is stifling to personal insight, imagination, and innovation; progress in general (see the Dark Ages).
I find it very funny that western religion is always playing catch-up with scientific (and societal) progress. I'm sure I don't have to provide those of you reading with examples of this, as you all are probably very aware of them yourselves (and I know I'm not being fair to all religions, but I am speaking mostly of The Catholic Church). Similarly, I find it funny that this progress commonly comes from someone labeled a heretic, atheist, or generally hell-bound (again, do you need me to provide examples...?). At some point, if it weren't for their blind hypocrisy, this group of people should realize the book that gives all the answers is entirely fictitious.