[tjradcliffe]

That's a very odd observation, because religious people as a population show very slight deviations from non-religious people. It is extremely difficult to tell by observation whether or not someone is religious, beyond church/temple/mosque attendance, which is equivalent to asking them.

Does he reference any data that would give his suggestion non-negligible plausibility?

[zvrba]

I've read the quote in the book "Wittgenstein's poker". After a bit of searching, I've found the following link: https://hengstmengel.wordpress.com/2010/02/22/philosophy-to-...

I believe the explanation you're looking for is under 3.1.

[coverup]

Do you have any data showing that religious people deviate only slightly from non-religious people?