Why does the concept of Religion and theory of Evolution constantly clash?

Why does Creationsim and Evolution always have to be battling one another? why does religion HAVE to put down Evolution? Why cant we have both? I dont see why we cant. Lets say god created the organisms capable of delivering life, and let them do the work from there on. Im not a scientist, but the idea of humans existing from the beginning of time isnt that plausible. I would be much more comfortable with a religion which could accept scientific values. Its just like back in Medieval times. people said Earth was flat and in the centre of the Universe, and that the moon and other celestial bodies were actually just illusions of light. They were wrong. So whats the chance of Creationists being wrong about Evolution? Im not saying that we should automatically take evolution as afact. But you should take it into consideration.