By which I mean, Northern Europe and most of Western Europe. But that wouldn't make a catchy title.
I just don't get it. I thought when I started looking into it, I'd find fairly straightforward historical explanations. But every theory I hear or come up with myself seems to have holes in.
The UK, for example:
Up to at least the first half of the 1600s, the British Isles were just as batshit crazy with religion as the average Puritan settlers to North America a century later. We were putting animals on trial and executing them for crimes including theft and bestiality, suicide was both a serious crime and a sign of possession by the devil, after which the body would have a stake driven through it like a fricking vampire, and Catholics and Protestants were taking turns to kill and persecute each other as the state religion ricocheted wildly between the two.
Fast-forward to 1928, and the following exchange happened in parliament:
One member:
"It is perfectly ridiculous that an assemblage that contains a number of atheists should vote on the inner politics of the Church of England."
Another's response:
"I don't think there are any atheists here, not really. We all believe in some sort of a something somewhere."
Fast-forward further to the present day, and over half of us don't believe in any gods at all, and most of those who do are either first or second generation immigrants or are so vague about it that they can't accurately be labelled as Christians even if they use that word for themselves for various reasons.
Meanwhile, 40% of Americans are Creationists. The US has "In God We Trust" on its money, and we have Charles Darwin on ours.
What the hell happened?
If I could figure out the secret, I'd bottle it and export it all around the world!