1) There are some big holes in the map, but if you did a 2D scatter-plot using a combined index of development level and percent Islamic, you could account for the majority of the variation.
2) The Czech Republic sticks out in Europe (as does France, as well as my ancestral German-speaking homelands.) But China is obviously the big one here. Is this good? Or more pointedly: is atheism a choice in China? I submit that the same people who grow up unquestioning atheists in Beijing would be unquestioning Mormons in Salt Lake City or unquestioning Wahabbis in Riyadh.
I can't speak for the whole atheist community but I know I would rather live in a country that is majority theist but has freedom to choose (e.g. Spain) than a country where atheism is mandatory, as in China. This is not the kind of separation I would want. Indeed, one of the things that dictatorships invariably dictate is that everyone either follows a specific religion (which of course they control), or that no one follows any religion - because dictators don't want competition for their arguments from authority. China has its cake and eats it too in this sense, because while it forbids religion in most places, it mandates people follow a Lama of the CCP's choosing, rather than the Dalai Lama. It's like a Monty Python sketch! Got that? A compulsorily atheist government is meanwhile telling some of its people (based on their ethnicity) which religious leader to follow. Completely inconsistent, unless of course it's just about controlling people. This might be funny, if over a billion people weren't living like this. Meanwhile, Tibetans are settling on Salish and Kootenai Reservation territory in Montana. Maybe I missed it but I don't see too many Native Americans trying to move to China...