I've heard lots of atheists say that despite their rock-solid belief that it's all fairy stories, they still enjoy singing Christmas Carols in church. The high-priest of modern day atheism, Richard Dawkins calls himself "culturally Anglican" (Douglas Murray, another prominent atheist says the...
I've told my sons they can be whatever they want and believe in whatever they want except for 2 things: if they become socialists or Man U fans then I'm disowning them. Perfectly reasonable, I think.