"(I'll leave it to the rest of you to flesh out the issues where some goof is able to convince a court clerk to perform a union between them and their cat and how to deal with the insurance claims)"
again, another person goes all slippery slope, red herring on us.
where has this been a discussion about humans marrying animals?
your "real issue" that you bring up is bass-ackwards.
it's not a question of the state interfering with the churches' stance.
it's the churches' stance interfering with secular law.
marriage is secular.
christians, muslims, agnostics, atheists, satanists, faithless, whatever - can all get married.
religion has nothing to do with it.
so why does your church have any say over the issue?
the argument people have against same-sex marriage is based on the biblical definition of marriage.
the state has to license marriage, because with marriage comes other secular rights (healthcare, dependence, property ownership, etc).
and what if you have a particularly liberal church that says they will marry same sex couples?
how about churches that hvae gay ministers?
wouldn't it be ironic if that minister is allowed to preach, but not be married in the church?
what a mess of major proportions you are headed for.
contrarily, the church is the entity that needs to get its hands out of marriage, other than for ceremonial rites.
if something is legal, it doesn't mean you have to do it.
if you go to a bar, you can drink a coke - you are not forced to drink alcohol just because it's there.
opening up rights to people does not diminish your ability to exercise or refrain from said right.