Allie,
First, thank you for posting, and telling your story. I also supported same-sex marriage, back when I believed the only objections were religious. In fact, I came to the same conclusion you did - I thought we should change the definition of marriage to include same-sex unions, while allowing churches to "opt out" if they choose not to conduct same-sex marriage services. It was only after I began to understand the complexity of the issue that I opened my mind to the possibility that society actually benefits from the traditional definition of marriage, and that there are valid reasons to oppose changing it.
I also now believe the solution of changing the definition of marriage while at the same time allowing churches to refuse to perform same-sex marriages is not a viable one.
One reason I believe this solution would not work is the current situation with the Boy Scouts of America. Boy Scout membership requirements exclude homosexuals. The ACLU has been very successful in litigation prohibiting any government sponsorship of Boy Scout activities, preferential access to government resources, etc.
With this precident, it seems highly likely to me that a change in the legal definition of marriage will result in churches being forced to choose between performing same-sex marriages or losing their tax-exempt status. An even greater concern is that churches which continue to refuse to perform same-sex marriages be sued for hate crimes.
Because of this very real threat to freedom of religion, the solution which struck you as silly actually makes a lot of sense. Allow a civil union with the full weight of marriage, including the rights and priviledges of marriage, yet called by another name. This is the the only solution I can think of that would allow society to permit the union of same-sex couples while at the same time guaranteeing the 1st Amendment right of Freedom of Religion - churches would be allowed to continue to perform traditional marriage ceremonies and remain faithful to their religious doctrines.*
* [edited to add: this is assuming society decided it wanted to allow same-sex unions, and grant them the rights of a marriage. I am not saying I think our society should do this, only that if it decides to do this, then the way to go seems to me to be to create a separate institution.]
