A new way to look at the Same-Sex Marriage issue

This, I think, is a new way of looking at the issue of same-sex marriage:

What we're talking about is CIVIL marriage, not religious marriage. No one's talking about forcing churches to perform same sex ceremonies....

BUT!!!! Churches (and often Christian ones) want to restrict CIVIL marriage based on their religious beliefs.

I say that this is a violation of the 1st Amendment. The Church is trying to impose rules on the State, and the first sentence of the first amendment begins with "Congress shall make no law respecting an establishment of religion......."

If rules for civil society are made based on what the church says is right or wrong, isn't that respecting an establishment of religion?