Is religion the reason the world is not peaceful?

Many atheists will assert that religion causes wars, genocide, persecution, and many other terrible things. If religion was removed from the world, then would the world really be that much better off?

The Soviet Union was officially secular, supported atheist ideology and suppressed religion througught its existance. By far, the consensus figure for those that Joseph Stalin murdered when he ruled the Soviet Union is 20,000,000.

That is right. The most recent country to be run by an atheist ideology, killed over 20 million people! So let me ask the question again... "Is religion the reason the world is not peaceful?"