Fun Fact: For a long time you couldn't get married in a church precisely because the christians didn't consider marriage to be something that should be their responsibility.
In honesty so much of what the anti same-sex marriage take for granted about what constitutes "traditional marriage" isn't even traditional for their religion. They have no idea how these ideas have changed so much in the last two centuries (let along the centuries before that). They have little to no understanding on historical context when they make their arguments. For example: in many European countries there weren't even ceremonies to declare a couple was married. It was very common for a couple to shack up and have kids and they were considered married by their community. They only important consideration was that the couple could support themselves financially (and were of an acceptable age) - this was what the christians were doing even though modern christians would find that immoral.
In honesty so much of what the anti same-sex marriage take for granted about what constitutes "traditional marriage" isn't even traditional for their religion. They have no idea how these ideas have changed so much in the last two centuries (let along the centuries before that). They have little to no understanding on historical context when they make their arguments. For example: in many European countries there weren't even ceremonies to declare a couple was married. It was very common for a couple to shack up and have kids and they were considered married by their community. They only important consideration was that the couple could support themselves financially (and were of an acceptable age) - this was what the christians were doing even though modern christians would find that immoral.