The Pew Research Center released a new poll this morning updating its measure of public belief in the misperception that President Obama is a Muslim (coverage: NYT, WP, AP). The news is not good -- belief that Obama is a Muslim increased from 11% in March 2009 to 18% now, while belief that Obama is a Christian declined from 48% to 34% and the group who said they didn't know increased from 34% to 43%. Here's a visualization of change in beliefs about Obama over time using the full time series from the Pew questionnaire (PDF; click graphic for larger version):
As Pew notes, "The view that Obama is a Muslim is highest among his political opponents (31% of Republicans and 30% of those who disapprove of his job performance express this view)." If we compare these results with those from March 2009, it's clear that Republican beliefs about Obama's religion have dramatically shifted (click graphic for larger version):
The most important issue, though, is why the misperception has increased over time. The Washington Post story does a good job of breaking down different possible explanations:
White House officials expressed dismay over the poll results. Faith adviser Joshua DuBois blamed "misinformation campaigns" by the president's opponents...
Among those who say Obama is a Muslim, 60 percent say they learned about his religion from the media, suggesting that their opinions are fueled by misinformation.
But the shifting attitudes about the president's religious beliefs could also be the result of a public growing less enamored of him and increasingly attracted to labels they perceive as negative. In the Pew poll, 41 percent disapprove of Obama's job performance, compared with 26 percent disapproval in its March 2009 poll.
More than a third of conservative Republicans now say Obama is a Muslim, nearly double the percentage saying so early last year. Independents, too, are now more apt to see the president as a Muslim: Among independents, 18 percent say he is a Muslim, up eight percentage points.
It's extremely difficult to distinguish between these explanations in poll data; both are likely to play a role. In particular, as Republicans and independents view Obama more unfavorably, they're likely to be more receptive to negative information about him, including false claims about his religion.
For more on why it's so difficult to correct misperceptions like this one, see my Political Behavior article with Jason Reifler (PDF). See also our working paper testing different approaches to correcting the Obama Muslim myth (PDF), which I discussed on NPR's On the Media last year.
Update 8/19 10:20 AM: Time conducted a survey this week (August 16-17) that found similarly disturbing results. Using different question wording and response options, they found that 24% of Americans believe Obama is Muslim:
16. Do you personally believe that Barack Obama is a Muslim or a Christian?
No answer/Don't know: 24%
By contrast, here is the wording for the Pew question:
Now, thinking about Barack Obama’s religious beliefs... Do you happen to know what Barack Obama’s religion is? Is he Christian, Jewish, Muslim, Buddhist, Hindu, atheist, agnostic, or something else?
While it's possible that the misperception increased due to Obama's comments on Friday about the proposed Muslim community center near Ground Zero (Pew's poll was conducted July 21-August 5), the differences between the questions mean the results are not directly comparable.