Well you asked. Don't blame if you get incredibly huffy and offended at what I'm going to say.
Karl Marx in his introduction to Contribution to the Critique of Hegel's Philosophy of Law said that: "Religion is the opiate of the masses."/ "Religion is the opium of the masses."
You might want to read Karl Max on Religion - Religious Atheism and also visit the excellent Marx/Engels Internet Archive.
I'm not sure that I want to go into detail in relation to this issue. Religion is a topic that generates strong feelings. Maybe I'll just give you a link to Yahoo's web links for atheism. I'm happy to receive e-mail on other aspects of my site and thoughts - but not this one. I don't try to convert anyone and I don't like anyone trying to convert me either.