At Secular Right, mupetblast asserts that the association between atheism and leftism is dissolving in the US. Given his vantage point, that may be little more than wishful thinking.
The percentages of GSS respondents, by year and by political orientation, who self-identify as either atheist or agnostic. To avoid racial confounding, only whites are evaluated:
The following shows how much more likely liberal respondents were, by year, to self-identify as atheist or agnostic than were conservative respondents. There is some noise from survey to survey, but to the extent that there is a trend at all, it appears to be in line with general tendency for Americans on opposite ends of the political spectrum to display wider and more acute disunity on, well, virtually everything:
1988 -- 3.36
1991 -- 1.61
1993 -- 2.71
1994 -- 2.04
1998 -- 3.02
2000 -- 3.04
2006 -- 4.57
2008 -- 5.03
2010 -- 3.30
2012 -- 6.62
2014 -- 3.53
A lack of theism, of religious affiliation, and of worship attendance increasingly characterizes people of all political orientations, but the change has been most pronounced among self-described liberals.
The presumption that most leftists are atheists is incorrect (at least for another generation or two). The assertion that most atheists are leftists, however, is currently accurate--among those surveyed between 2010-2014, 52.6% of atheists and agnostics self-described as politically liberal.
In fairness to mupetblast, his point is that the natural inclination of militant atheists like Richard Dawkins to say iconoclastic things is butting up against all the emotional safeguards that have been erected by the cultural Marxists to shield the protected classes from any perceived criticism of any kind, ever. Here is to hoping he is on point there.
GSS variables used: GOD(1-2), YEAR, RACE(1), POLVIEWS(1-3)(4)(5-7)