Why do so many people think Pres. Obama is a muslim?

Citing his long-ago memoir "Dreams of My Father" (written long before he ran for any office), and doented membership over a couple of decades in Christian churches, it's been demonstrated over & over that President Obama's of the Christian faith. In fact, t has been so well studied and doented, that it appears that this constant drumbeat of "Obama's a muslim" is pure partisan palaver. (and THAT, I think, is racial in origin; too many Americans just can't accept that a black man won the 2008 presidential election fair and square, and they're out to discredit him any way they can.)