I also believe in one God, and I must assume that Muslims worship the same God, albeit a bit sideways.
The biggest difference is that Muslims believe God tells them to kill and conquer, and the rest of us believe God tells us to save and invite.
My concept of God is incompatible with the Muslim concept of God. Nuff said.
There was a time when Christians believed their God wanted them to kill and conquer. But that was nevertheless the same God Christians worship today.