Religion, politics, and support for same-sex marriage in the United States, 1988-2008

We examine how religious and political factors structure support for same-sex marriage in the United States over the last two decades. Using data from the General Social Surveys, we show that respondents who identify more strongly with the Republican Party, sectarian denominations, and those who subscribe to biblical fundamentalism and political conservatism are substantially more opposed to same-sex marriage than are other Americans. Heterogeneous ordinal logistic regression models show that these religious and political factors have become more important over the last two decades. Cohorts born after 1945 became substantially more supportive of marriage rights between 1988 and 2008, but shifts in support for marriage rights were less sizeable for persons affiliated with sectarian denominations, religious fundamentalists, Republicans, and political conservatives. Estimates from structural equation models show that religious factors influence political conservatism and Republican identification, yet both religious and political factors have significant and substantial independent direct effects on support for same-sex marriage.