BWL, here are links to places I think explain the "ordinariness" of the mixing of militarism, religion, and patriotism in the minds of way too many Americans.
Here is a group calling itself the American Center for Law and Justice that typifies the sort of American Christian religious patriotism that has so gripped the nation in the wake of 9/11 especially, but has it's roots in the Reagan doctrines, and Republican demonization of those who opposed the Vietnam war especially.
And here is an article I just found out googling, that I think explains it pretty succinctly the very question BWL raises:
"(A)s Americans we do not belong to a single racial group, do not share the same religion, and are mostly relative newcomers to the national soil we inhabit...What is it, then, that binds us? The answer can be found in a set of ideals and myths pervading our national consciousness that has been growing for two centuries. Whether we admit it or not, even if we claim we are not religious, we frequently tend to operate according to the prophetic vision, dogmas, and rituals of a generally unacknowledged religious tradition. Our behavior belies this as we take pilgrimages to its shrines, view its relics, sing its songs, celebrate its holy days, show respect to its saints and martyrs, and respond to its symbols. The United States is indeed a religious nation, but its unifying religion is not Christianity or any other world faith -- not even "the religion of secular humanism," as has been claimed of late. It is instead a unique national belief system best called _Americanism_."