Aha! I spend all my days contemplating this!!!
Religeon has been helpful to mankind to an extent. While the messages they give are hardly ever actually followed, they keep average people in check. Mankind is egocentric and greedy by nature, so there wouldn't be much hope for civilisation without something to surpress that. Religeons were the solution to that. Meaning, they make people behave themselves (usually), while giving them a sense of purpose in life, and making them feel important, so they don't seek more than they have already. "Religion is the opiate of the people" - Karl Marx.
With people actually working together now, technological advancement was possible. And through that, advancement in other areas. So, over the years, religion has greatly benefited humanity (forgetting holy wars, crusades e.t.c.).
But now we've come so far and are beginning to understand so much about the world around us, the universe, and ourselves, that it's contradicting religion. And while religion has an explination for pretty much everything, what science has explinations for can be proven and backed by evidence. And that's where Atheism vs Theistic religeon, logic vs tradition*, and left wing vs right wing all come from.
And the two can't co-exist peacefully anymore - science is now going into things such as stem cell research, cloning e.t.c. and religion opposes that. Science is also finding things that are making us realise what humanity is - just another species on the planet, no better or worse than any other. Which takes away the sense of importance religion gives. Which is why groups such as christian fundamentalists take the bible literally and use it to disprove (Yes, disprove the one with evidence when you have none) science.
I think that in the end science will win out (as in, hundreds of years), but before that can happen, human thinking needs a major reform - both as a species and individually we need to become more positive, and less arogent and self centered. We need to do things and help each other because we want to, not because we feel we have to.
So basically, religion has been helpful, but its got to the point where its now holding us back. But science won't win without major reform in our thinking.
Those are just my views on everything.
* I couldn't think what the opposite to tradition was called. I thought of futurism, but that was an art movement :p