This is a start that can't be finished. All churches will never accept the idea of gay marriage, so all that will happen is a fractured landscape of unions.
The problem is the word "marriage" having 2 meanings. One is a legal definition, upon which rights are conveyed and the other is a religious one, where each religion has its own ideas. Since every religion has their own separate idea of what a marriage means, there can be no definition. With no definition, marriage isn't a usable word in the context of religion without a defining prefix such as Catholic marriage, Jewish Marriage or Muslim marriage.
If States or countries create their own definitions, then once again, the word gets watered down to California marriage, German marriage, or even Camden County marriage! Where does it stop?
For a start, legal recognition needs to be completely separate from religious. A purely religious marriage should convey none of the legal benefits of the legal requirement. Anybody should be allowed to marry in the eyes of the law. Let churches sanctify their own marriages under their own definitions. Until we completely separate the two, where neither recognizes, nor crosses over into the other's territory (practical vs. spiritual), will we be able to settle on a working recognition of any desired union. Unfortunately, gays are pushing to be recognized in a spiritual way while churches are pushing for legal sway. I think there were some pretty good ideas about the separation of church and state around 229 years (and one day) ago.. Shame we've wandered a bit off the path... - j