When did "one man, and one woman" become a part of the christian view of marriage?

My best answer will be to respond to the first answerer. Reformation means "make changes in." So to say that homosexuality was "never" accepted in Christianity is asinine by this definition. It was reformed to include that homosexuality is bad. Prior to that, it was probably accepted. And either way, it is ignorant to view it as "bad." Practically every species of animal has homosexual tendencies, including humans. Quit trying to make people feel bad for just BEING.