British television had a series in 1997 called Secret Lives and one program was about L. Ron Hubbard, founder of the Church of Scientology. It is quite fascinating.
Some supporters of religion argue that the very fact that their religion has lasted so long and spread so widely must mean that there must be something to it. But if people now, with all the information at their disposal, can be suckered by an obvious conman like Hubbard into following his religion, it should not be surprising that people a couple of thousand years ago fell for it too. Joseph Smith and the Mormons is another good example of how modernity does not inoculate the gullible against hucksters.
(Thanks to Norm)
I’ve also heard the common explanation that ‘there must be something to religion, since most people historically have believed in it’.
I remind them of Slavery. Another practice that was -- and continues to be! -- widespread. But just because everybody’s doing it doesn’t mean it’s right.
But this line of argument doesn’t go very far. People who want to believe are offended by the slavery reference. I have yet to find a better substitute, though. The shock value is great.