I don't care what gays and lesbians do behind closed doors. They simply don't have the right to redefine the meaning of marriage for the rest of society.
They can't define it for me, regardless of what the law says. Mine is a sacrament, and a covenant, and would be with or without legal sanction. If they want legal sanction for theirs, that doesn't define mine.
But that will not stop the state from teaching children in public school that A truly does equal B despite the teachings of the parents.
A short jump from that position will be the state imposing its will on religious institutions through hate laws which are already working their way through the Senate.
These aren't slippery slopes, they are reality.