But if we're having an argument about how marriage is currently handled by the government and how it should be handled by the government, then it's as valid to say "they shouldn't recognise marriage at all" as it is to say "they should allow it for both gay and straight relationships".
Using your argument, Muslims should be able to argue that the government should recognise polygamous marriages also. Using my system, everybody is automatically treated equally whereas, with the current system, Muslims etc are treated worse than homosexuals and monogomous heterosexuals.
Using your argument, Muslims should be able to argue that the government should recognise polygamous marriages also. Using my system, everybody is automatically treated equally whereas, with the current system, Muslims etc are treated worse than homosexuals and monogomous heterosexuals.