Just don't use the power of the state to do it.
Protecting the sanctity of marriage is not "gay bashing."
I could not agree with you more. But the sanctity of marriage should be protected by social institutions that are at least geared toward protecting sancitity, like churches.
The government does a terrible job of protecting the sanctity of anything. In fact, government involvement will pretty much guarantee the de-sanctification of just about anything.