How much money do you suppose has been spent by the Christian right over the last 5 years in opposition to same-sex marriage? No, I don't have any numbers handy. But if you recall California's Proposition 8 fiasco alone, you'll get a sense that we're talking about some serious cash being spent on the goal of preventing same-sex couples from marrying.
Now, how much money do you suppose has been spent in the last 5 years to prevent people from cooking with yeast, wearing blended fabrics, eating shellfish, or decorating Christmas trees? Again, I don't have numbers, but I'd be willing to bet that the answer is "not much." These things are condemned in the same book many Christians point to as providing their rationale for condemning homosexuality.
Why is it okay to ignore some of what one's god supposedly condemns while spending large sums of money to oppose others? What makes the idea of others having the legal right to marry (or any other rights which one enjoys for oneself) so much more objectionable than all the things Christians ignore in their book?