I don’t it’s so much that people never talked about religion or politics, as much as the way they’re regarded now.
First religion: Twenty or thirty years back society was a lot more homogeneous and you’d rarely encounter anyone who wasn’t a similar religion to you. If you weren’t particular religious you wouldn’t dream of forcing that on anyone and you wouldn’t have dreamt of dissing the religion of your one Hindu neighbour. You’d have just been politely respectful to each other. The one exception in Britain would be something like the Troubles, where of course religious infighting (or proxy political/power struggles which hi jacked it) resulted in your local arndale getting blown up. That aside, most native Brits aren’t very vocal about religion, churchgoers or not.
As for politics, I think people have always talked about that. I grew up in quite a politically aware household, and was a young teen in the miners strikes, so politics was something that was around you a lot when I grew up.
What’s changed i think is that people used to be able to talk about it, or really argue about it, and then carry on cordially as before. I remember as a student having some arguments with people (I was colossally wrong, looking back) and then us changing the subject to the pop charts or what we’d do that weekend and it was all forgotten. Political opponents were just that - an opponent. Not an enemy. This whole screeching culture of demanding your enemies be utterly destroyed, and that anyone who doesn’t agree with you is your enemy? That’s new. And awful. Everything being political is new. Identity politics is new. You can’t talk about politics anymore, you have to BE politics. And before you got good political analysis in the papers, from knowledgeable people, well written and well researched. Now journalism is in the gutter and it’s all hot takes with zero real analysis, apart from a very few decent journos still trying to keep it going.