Well listen: Islam said to kill those who were muslims but abandoned the religion, it's a punishment. But it never said to kill non-believers who don't follow it, on the contrary, they have their own freedom of thinking, and they must NOT be forced to the Islam, they have to accept it on their own.
And the reason we muslim countries haven't banded together, is because our rulers, and a lot of people who call themselves "muslims", have strayed from the path of true Islam... Muslims used to be a great force in the past, but now, most people have just "inherited" being a muslim and don't act as one... So please don't judge the Islam by the acts of nowadays muslims (even I don't consider myself as a true muslim T^T).
Thank you, and sorry for the long text...