A growing number of Americans believe that Barack Obama is a Muslim, a new survey conducted by the Pew Research Centre [2] shows. The proportion of people accurately identifying him as a Christian has also declined since his inauguration as president.

The statistics get more worrying when you delve a little deeper: 67 per cent of those who identified Obama as Muslim disapprove of his job performance, compared to a 29 per cent disapproval rating from those who think he is Christian. As Obama's approval ratings [3] continue to founder, it seems that perceptions of his political performance are increasingly being linked to assumptions about his religious identity. However, his policy decisions are considered to be less influenced by religion than those of his predecessor.

Nearly one in five Americans now identifies Obama as a Muslim, up from 11 per cent in March 2009. The increase in this perception is particularly marked among Republicans (up 14 per cent in the same period) and conservative Republicans (up 16 per cent).

Crucially, this poll was conducted in early August, before the president's intervention in the Ground Zero mosque controversy [4], which has provoked a wealth of anti-Muslim dissent [5] from some quarters. The Pew findings are echoed in a recent Time [6] magazine poll, in which 24 per cent of those surveyed said they believe Obama is a Muslim. Almost a third said that Muslims should be barred from running for president at all.

Internet conspiracies surround Obama's birth and religion have been around since well before the 2008 election, but the notion that Obama was a Muslim received more attention after a supporter of his Republican opponent John McCain repeatedly referred to him as "Barack Hussein Obama" [7].

As to where this perception is coming from, Joshua DuBois, the White House adviser on faith, has blamed [8] "misinformation campaigns" by political opponents. Yet the survey tells a slightly different story. About 60 per cent of those who identified Obama as Muslim said their source was the media, but one in ten cited "Obama's own words and behaviour".

Considering the man is very forthcoming [9] about his faith, and that the news wires regularly run reports [10] about him attending Baptist services, it is hard to pin this entirely on the media. Given the swell of anti-Muslim sentiment [11] across the US as the Ground Zero controversy intensifies, the misconception isn't going to be corrected any time soon.