When asked about why they support gay marriage, most people who say they do describe personal experiences. About a third of those who say they have shifted to supporting the practice say their views changed because they know someone – a friend, relative or acquaintance – who is homosexual, and almost half say that over time they have come to view same-sex couples as similar to heterosexual couples.
Those who have not shifted to supporting gay marriage, but say they are opposed, typically cite religious or moral concerns as the main reason. Many also suggest that allowing same-sex marriage will encourage the assimilation of gay people into mainstream, heterosexual culture to the detriment of their unique community.
The change in Americans' attitudes about same-sex marriage has occurred alongside a shift in views about homosexuality as a whole. Over the past decade, the percentage of Americans who said homosexuality should be accepted and not discouraged by society has risen by 10 points to 64%. Moreover, there has been a parallel decline in the proportion who say that marrying one's sexual orientation goes against their religious beliefs.
Among subgroups that had historically been most resistant to legalizing gay marriage, opinions have become progressively more positive, with the exception of older adults and Protestants who continue to be predominantly opposed to it. Even Americans who attend church weekly have grown more supportive of same-sex marriage over the course of Gallup's trend spanning more than two decades.