Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.
Let's look at that statement in bold for a moment, for a bold statement it is.
There's a tendency in recent years for American Christians, led astray by the Fundamentalists and Dominionists, to look askance at the Wall of Separation between Church and State.
The problem is that they're taking it out of historical context.
The "Establishment Clause" and the "Free Exercise Clause" are there to keep other churches from telling your church how to worship.
It was originally written to keep the peace between competing Christian sects, and to protect any dissenters from the fallout between them.
Proposition 8 supporters insist that they're protecting "Freedom of Religion", but, whether they realize it or not*, their initiative will infringe upon the freedom of at least one major Christian denomination and many smaller ones who do accept, support, and will perform same-sex marriage ceremonies.
Under current law, no church is required to perform such ceremonies.
*I am sure the more fervent Fundamentalists and Dominionists are well aware that they're imposing on other people's religious freedom, but dismiss that because tehy don't consider them to be practicing a "real" religion. I am willing to give the benefit of the doubt to the rest, however, and assume that they simply haven't viewed the question in this framework.