What are the problems with the "A song of ice and fire" series?

[SmartAlec]

So did the Crusades, what's your point?

I'd say that's not true; there were quite a few elements of 11th century Christianity that would be at odds with modern-day morality. By contrast, the Faith of the Seven seems quite capable of co-existing with other religions and does not condemn those who do not follow it, with more of a focus on charity, goodwill and trying to offer counsel. There seems no religious tension in Westeros. There seems to be no agressive push to, for example, evangelise the North.

Only in later books have we seen the Seven become more militant, but that change seems genuinely motivated by the ravages of war upon the kingdoms and its people.

Edit: In short, it doesn't feel like the kind of religion that would come out of this world.