Civil unions

As a way to deal with the fight over gay marriage, how about making the states only recognize a civil union, and leave marriage to churches?

Thanks to the First Amendment, here in the US we have separate civil and religious definitions of marriage.  A civil marriage is a complex contract with a large set of rights and duties between the spouses, and an equally large set of rights and duties related to other institutions, e.g., a presumption that they're responsible for paying each other's taxes, and the right to choose medical treatment for an unconscious or incompetent spouse.  A religious marriage is whatever the denomination says it is. (As a Unitarian, I can report that this question can be equally complex.)

In many cases, the civil and religious marriages happen at the same time, with the religious officiant deputized by the state, but a civil marriage is the same contract regardless if whether it's performed by an archbishop or an assistant town clerk.  There are plenty of cases where a civil marriage isn't recognized by a church (divorced Catholics) or vice versa (renegade Mormon plural marriages), which reinforces the point that they are parallel institutions.

So for the civil union idea, there's an issue of what it means and what it's called.  It seems to me that if its civil definition is truly identical to a civil marriage, then it is a civil marriage.  If it differs in some way, it's a second rate deal for Those People.  No question, for a lot of people the name matters a lot, although personally, I am 100% confident I know who my wife is, and I want the civil recognition that married people get, but I don't care what they call it.

I still think it's basically a tempest in a teapot, and when our kids are making the laws, the idea that there was a time when same sex couples couldn't get married will be ancient history.