In The Saint in New York, published 1935, author Leslie Charteris described New York, 11 years after the 1924 immigration cut-off, as "A greater Italian city than Rome, a greater Irish city than Dublin, a greater German city than Cologne..." He also described it as a "modern Baghdad where the ends of the earth came together," but that was just metaphor, also used earlier by O. Henry who called it "Bagdad-on-the-Subway," and was not meant to imply any large Iraqi population, unlikely under the old National Origins quota system.
Anyhow, it's in the sense that New York was a "greater Irish city than Dublin," that Barack Hussein Obama apparently meant when he told a Muslim audience that America "one of the largest Muslim countries in the world." This is statistically not true, especially since the estimated Muslim population of the US is under three million. (It used to be estimated as much larger, but it was the Muslim lobby doing the estimating.)
But of course, while the United States as a polity has no establishment of religion, it's a Christian nation. It was founded by Christians on more or less Christian principles, and the greater majority of its inhabitants are Christians. (Even Obama is nominally a Christian, enough of one to be disapproved of by Christopher Hitchens.)
But no one's allowed to say that. In Alien Nation, in 1995, Peter Brimelow, attempting to explain the concept of "nation" reminded his readers of the outcry that went up at every time someone "unguardedly described America as a 'Christian nation.'" That remains true today.