I can understand countries at war over food, what I CAN'T understand is how religion can be used as a reason for killing.

It's the ultimate oxymoron in civilized society.

Are we just all being led by the nose by politicians who are using religious creeds for their own gain and so turn us against each other?

Even Mohammad was a political man. He wanted Islam to spread. No different from people before and after him I guess OF ANY religion or political persuasion.