Indiana University sociologist Brian Powell published a study which analysed, among other things, why people opposed same-sex marriage.

These data include more than 2,200 one-time interviews with a geographically and sociodemographically diverse sample of Americans, and contain both closed- and open-ended responses on attitudes toward same-sex marriage, family, and sexuality.

Our research shows that disapproval of same-sex marriage and animus toward gays and lesbians are, indeed, highly correlated and that people who hold one of these stances usually hold the other as well.

Nearly all respondents (90%) who strongly oppose same-sex marriage also believe that “sexual relations between two adults of the same sex” is “always wrong.” In contrast, approximately five-sixths (83%) of responses who support same-sex marriage view same-sex relations as “not wrong at all.”