"With regard to Obama, the poll found that misperceptions about his faith persist.

About half of registered voters correctly say Obama is a Christian. Seventeen percent misidentify him as a Muslim, 3 percent say he adheres to some other faith and 31 percent say they are unsure."

That is quoted from an article that speaks about the poll. The misunderstanding? Look at the last phrase of the quoted stuff: the 31 percent are not saying they don't know whether Obama is a Muslim; they are saying they have no idea what his religious faith is. The only people who misidentify him as Muslim are the 17%.