The Muslim religion is probably the greatest threat to humanity today. Take a religion that totally integrates faith and government and believes in spreading it's message through armed conflict, put it in a position of watching the infidels all around it, who are destined for Hell anyway, gather wealth and power, and you have a recipe for apocalypse.
I am not saying that Christianity, Judaism, Hinduism or the Nordic Pantheon are superior to the Muslim belief system, only that most of the others have received a generous dose of rationality over the past 2000 years, and that tends to reduce the number of frothing, raving fundamentalists within them. The sad thing is that true believers, Christian and Muslim alike, interpret their prospective word-of-god pamphlets (the Bible and the Koran) literally, and literal interpretation is rife with intolerance.
Religious fundamentalism is organizationally-imposed madness. How else could you induce relatively sane humans to decapitate innocent children, impale babies, burn people at the stake, and fly planeloads of people into skyscrapers, all the while convinced they were doing GOOD?
Personally, I believe it is time for the Human Race to declare religion in all its forms to be baseless, medieval, mythological bullshit, elevate ethical behavior to a science which can be studied and applied, turn churches and mosques into universities or museums, realize we're all going to die and there will be no harps or virgins, and get the fuck on with the serious business of preserving the human race and the planet.