Why do some people favor an amendment to the US Constitution banning same-sex marriage?

Answer 1

I believe that people are afraid of what they do not understand.

In general, opposition to same-sex marriage comes down to two issues:

1. Certain religions are against homosexuality (they consider it a sin), and thus, allowing a sinner to take part in a holy sacrament violates their religious beliefs.
2. People have an "ick" factor around homosexuality due to cultural bias; that is, they consider homosexuality deviant behavior, and don't want the government sanctioning something they feel uncomfortable with. Frankly, this is comparable to the way many people felt about inter-racial marriages prior to about 1970.

People who fall into one of these two categories now recognize that in the current legal framework, same-sex marriage is going to become legal, in no more than a decade at the most. Thus, they seek to change the legal framework itself, which is why they are pressing for a Constitutional Amendment, as modifying the Constitution is almost certainly the only way that same-sex marriage can be stopped.