These political differences in support for gay marriage may stem from even larger differences by religion. Americans who say religion is “very important” in their lives oppose legal same-sex marriage by 70% to 27%. In contrast, Americans who say religion is not important to them support gay marriage by just as wide a margin.

Differences on the issue are also apparent by religious affiliation. Notably, 81% of Americans who claim no religious affiliation favor legal same-sex marriage. That compares to 48% support among Catholics and 33% among Protestants (including those who identify as Christian but do not specify a particular Christian denomination).