Same-sex marriage used to happen in Christianity.

Contrary to myth, Christianity’s concept of marriage has not been set in stone since the days of Christ, but has constantly evolved as a concept and ritual. Prof. John Boswell, the late Chairman of Yale University’s history department, discovered that in addition to heterosexual marriage ceremonies in ancient Christian church liturgical documents, there were also ceremonies called the “Office of Same-Sex Union” (10th and 11th century), and the “Order for Uniting Two Men” (11th and 12th century).