Conversation with a conservative -- Is there religious war between Islam and Christianity?

Many people disagree with me about many things.  Sometimes you should hear from one of them first, before you read my ideas on the subject.  This is one of those times.

Are we currently experiencing a religious conflict between Islam and Christianity?  Do the followers of the world's two largest religions have such different sets of social, political, economic and faith-based beliefs that they cannot coexist peacefully until the time comes when one is unequivocally predominant?  Are we asking ourselves these questions because of a rising force in the world that should be labeled "radical Islamic terrorism?"  Should the President of the United States clearly state that these things are so, and that America is in a battle with radical Islamic terrorism?