... only 49% of Republicans think the religion of Islam should even be legal in the United States with 30% saying it shouldn't be and 21% not sure.And that's not the result of tricky question wording:

But pundits and "data journalists" will just dismiss this, as they've dismissed repeated polling in which large numbers of Republicans have said they believe or suspect that President Obama is foreign-born and a Muslim. Here was Harry Enten, now of FiveThirtyEight.com, in a 2012 commentary on that subject for The Guardian:
The belief that Obama is something other than a Christian born in the United States has everything to do with ideology. Republicans are just perturbed beyond belief by Obama, and when you offer them a prompt about said person, they are likely to say anything that might be seen as a negative. It's as Julian Sanchez (via [The Atlantic's David] Graham) put it, "symbolic belief":It's marvelous that these data savants are mind-readers. It's amusing that they're the sort of people who usually scorn others for rejecting hard data in favor of hunches, yet they insist that hard data of this kind ought to be massaged because it just doesn't feel as if it's literally true.
"Propositions you profess publicly, maybe even sincerely believe, you believe; even while, on another level, there's some part of you that knows better."
I'd like to offer a challenge to GOP-insanity skeptics. You don't believe Republicans really think Obama is a Kenyan-born Muslim? You doubt that large numbers of them really want Islam outlawed in America, or think maybe it should be outlawed? Then conduct some focus groups of poll respondents who say these things. Design them whatever way you think will tease out the respondents' true beliefs -- I leave that to you, or to whichever professional you sign up to do the work. I think these people, under persistent questioning will confirm that they mean these things very, very literally. Ask them. Let's see who's right.