Of course a higher proportion of scientists in 1850 were Bible-believers. Religion was a pervasive element in education and even in journalism. Popular preachers were local celebrities.

Why "of course"? Where is your evidence for this? Saying "of course" doesn't make it any more true. If you want an assertion, I would assert that religious belief has never been stronger (and do shed all remnants of Christian imperialism as you read that). I would also assert that there is nothing at all stopping the jobbing scientist from being a believer. Let's not get carried away with the notion that there are thousands of scientists out there who find that their science and religion clash. They just don't. As for religion being a pervasive element, tell me how much more pervasive it could possibly be than it is today in the US. Or Israel. Or in a dozen or more Islamic countries. And consider that popular preachers in Iran, for example, are a damn sight more than just local celebrities. Things may have changed slightly less than you think.