If you polled democrats and asked did Clinton get impeached for getting a BJ you would get a very high number of yeses even though most of them know it isn't true. Most republicans don't realty believe Obama is a Muslim but they do think he has sympathy for them and that he tries to downplay Islamic extremism. Saying he is Muslim is more of a running joke than a belief and a way of saying he does not believe the way they believe. Not really that much different than the dems insisting Bush was bumbling fool who could barely complete a sentence.
The 43% is probably 85% fuck you.