There are literally HUNDREDS of dead Americans killed by fellow Americans who were "assimilated into middle class America and were good friends with their American neighbors". Americans have and still do terrible things to one another in the name of religion. They also do it in the name of bigotry, phobia and for no good reason at all. One might do well to be wary of everyone, really, but that is a hard way to live.

There are also many Americans born in America, every bit as American as you and me, who are Muslim. Not sure where they fall in your dialectic. 

Your question about Americans demanding that other humans convert to their religion or die is laughable, given only the vaguest sense of American history. You must have missed all that stuff in junior high about Manifest Destiny and the displacement of native peoples.