Rictor: There were several states with no "faith", most recently the Communist nations. Was there quasireligious political zealotry? Of course. That is where you'll find the universal, not in some need for the nebulous concept of a God (and, honestly, most of the gods were absolutely nothing like the Christian God, hell, a good number of them would better qualify as regular people with supernatural powers). The greater mass of people need a father figure watching over them telling them what to do, something to assuage their fear of the unknown, and a justification to hate those who are different from them. Religion provides all of these, as do political philosophies like fascism and Stalinism.
Presuming that in the long run totalitarian governments and other forms of political fanaticism don't overtake us all, yes, religion probably will stay, in one form or another. But it's important not to mistake why, and the events of the previous century in particular have made the reasons quite clear (though, really, there's evidence in every century of much the same).
Jaded? Hardly. The world is so much more interesting when you can't look at some glorious structure or improbable natual formation, glaze your eyes over, and say the big man in the sky did it. It's only when you look at the world from a standpoint of the real that you realize how damned intricate every little thing is.
Stu: Um, you're probably reading wrong. Atheism tended to get you a death penalty in Greek civilization, so even were it imaginable to most of the philosophers they certainly wouldn't have gone about making a show of it. There were a few who were critical of the religious dogma of the day, Socrates and co. in particular, but religion was pretty culturally endemic in the day. Also, have you seen Joe Average Christian? None of the Protestants (dirty heretics) I know even go to church, much less are capable of quoting passages from the Bible, and it'd be beyond most to even give a clear explanation of what's in the Old Testament. Religion is something paid lip-service to by the enormous majority of people, a cultural artifact rather than the result of any genuine convictions. Compare that to the extreme religiosity of even three centuries ago (never mind a thousand years, when people'd think nothing of hearing someone talk about a witch cursing their crops or seeing a satyr in the woods or any of a thousand other crossovers from the supernatural to everyday life that today'd merit a long trip to the nice place with padded walls), and, well... guess it all matters what you define "religion" by. The name Jesus will probably still ring a bell in a hundred years, but that may well be it.