Be a smidge more tolerant and don't worry about it.
Unless someone is actively trying to get you to join something ...
From an atheist perspective religion is just another form of ideology and there is plenty of that going around. 'Socially acceptable' ideologies with respect to all sorts of things are common in the workplace, we mostly just go on about our business because it's usually not hugely relevant.
The world is full if interesting things, be thankful you're not being pressed into the Russian Army or thrown in jail because you look a bit different.