Hello, I'm not understanding this thing that I keep seeing in the papers that reads, "the protection of the institution of marriage is our number one national priority." Can someone explain this to me?

I do understand that some people do not like homosexuality. I do understand that some people find it ugly. I understand that some people view it as a poor lifestyle choice. I understand what the rabbi in the film Trembling Before G-d meant when he translated a biblical phrase that is applied to homosexuality, one that means, "You're making a great mistake." I understand that. That's plausible.

I don't understand how "protecting the institution of marriage" is a priority of any kind, national or otherwise. What is this protection supposed to ensure? That gay couples, once married, are going to start preying upon unsuspecting little boys? The deductive link between "legalizing gay marriage legitimizes homosexuality" to "gay folks are going to ruin the lives of us regular people" is eluding me. Does anyone actually have a rationalization for this? If so, please share! I'm dying to know!