Atheists in church

[Spongebob]

Every church I've ever been to is much more complex than a chess club.

A church is just building with people inside that are playing fairytales.

That's certainly untrue.  As I said, every church (I should say most) is made up of a community of people who come together for more than just religious worship.  It's a complex mixture of culture, religion, community, relationships and more.  I know for a fact that there were non-believers who attended the same church I did (I've been to many over the years).  You appear to be applying your own experiences and biases and generalizing over all other churches.  This is almost always a mistake.  And regardless if we consider their beliefs to be fairytales (and I do), religious faith still has strong power to bring people together and to motivate people for good or bad purposes.  To say they are "just" playing fairytales is overly reductive.