Here's my take:
If he is a Muslim, fine. I'm realistic, and I'd only really have a problem with it if he was at all religious, because that would bring all sorts of trouble. But, the reality is, if he is/was a Muslim, he's not a practicing one, in fact, he is a practicing Christian. So that point is moot.
What I have a problem with is the discrepancies in the responses to this issue. Obama himself said that the call to prayer was the "most beautiful thing at sunset," and was able to recite a prayer in near-perfect Arabic. He attended a Muslim school in Indonesia and his classmates there all said that he was a devout Muslim. And now his half-brother Malik comes out and also says he was a Muslim.
The Obama campaign, on the other hand, has denied this from the start, posting on its website that "Barack Obama isn't and never was a Muslim." That is clearly not the case.
What I'm wondering is, why would he/his campaign lie to us like this? Sure, it might be something to hide if you want the votes of the ultra conservatives, but then you would also have to hide the fact that you're black. It shouldn't have been hard to predict the truth would eventually come out, but what are they trying to hide if they're still maintaining this story?