Blimey. I obviously don't take my staunch and lifelong atheism seriously enough! 
This is an atheist household - at least, I am, DH is, DS1 (7) is more militant than I've ever been, after his first year in school which was rosy-tinted awww-baby-Jesus-angels-fairies, but thereafter he developed an interest in Science! and a strict line in secularism.
DS2 is autistic and unlikely ever to believe in anything like a god.
And we do the lot. DSs go to CofE schools because that's where we live, and we go to their school church services and have even, willingly, been sucked into the crib service on the 24th because DS1 was in it once, I've helped out with Sacred Craft for it, and it's rather nice. Plus half the village get involved! We've even taken in a couple of Christingles, although they were pretty tedious. A major part of Christmas for me is going to hear Handel's Messiah. We have a nativity set (a tiny one) in the house as part of the decorations, it's pretty.
We also talk about Yule, and other old religions, and how Littlenose welcomed the sun back at the Fire Dance (Littlenose, anyone??) and how people in other parts of the world celebrate midwinter, and the solstice (though celebrating it isn't part of my background and I'd feel a bit forced introducing a Solstice Celebration now). It's all a mishmash with, probably, the Christianity on top, which is fine by me. It is, after all, most latterly, a Christian festival, as well as everything else it is. Doesn't stop me not having a devout bone in my body.
I wouldn't dream of telling DS1 not to believe in Father Christmas because he's made up. He might think god doesn't exist but he's also only 7, and I'm buggered if I'm going to muck around with his childish innocence and lack of logic, killing a lot of his joy at Christmas, by insisting that if god doesn't exist, neither does Father Christmas.