As I posted here a week or so ago, I'm worried that the religious right may be successful in their attempt to conflate marriage equality with a diminution of religious freedom.
Fortunately, here comes someone both smarter than I, and MUCH more informed about the legal issues surrounding the balance between the freedom to hold certain religious beliefs (and to act on those beliefs) and current laws forbidding discrimination based on sexual orientation. It's a longish post by Dale Carpenter but you can read it here.
Money quote: "While marriage and religious belief are one creature in the minds of many people, they are separate things in the law. Catholicism and Orthodox Judaism, for example, refuse to recognize secular divorce. But few argue that we should refuse to let people divorce for this reason. One can be divorced under the law but married in the eyes of the church. The statuses can be separated without a diminution of religious liberty. And nobody thinks that this de-linking of the two constitutes official oppression or the obliteration of religious freedom. Similarly, in principle, it should be possible to have a regime in which same-sex couples are married under the law but not married in the eyes of a given religion — all without extinguishing religious faith."