Comment 20 by Zeuglodon :

I don't think it would be less than a decade, though. On a naive estimate, if the number of self-proclaimed christians drops another 18% in the UK (to 36%), that's still only one country in the west. I dislike sounding like a party pooper, but I'm wary about getting optimistic over the forecast.

Count out the oldies - they'll be cramming for finals in churches, anyway... and I don't think that the battle for reason will be won only when the last person in the country is deconverted... No. I think, when secular principles are generally respected, faith stops enjoying special privileges and undeserved respect, when the majority of students graduating out of college are atheists, when Christianity & Islam & Hinduism are regarded as ridiculous cults, we'll have won anyway.

Also, I think, you are underestimating the positive effects of accelerating technological developments and free-er access to information. Heck! I think, a decade is good enough for even some developing, but generally educated nations to get there! And, by the way, have you heard of 'the tipping point'? I think, the celestial dictator will go the same way as Arab dictators... from one (educated) nation after another as each catches the wave of reason, i.e., whenever, it happens (though nobody can tell exactly when). But I suspect, it'll be roughly when the notion that ridiculous superstitions deserve some sort of respect goes away.