Fighting the Establishment
What does this mean? Fundamentally, it means that Congress (and, by the Incorporation Doctrine, state and local governments) can't give preferential treatment to the ideas of one religion over another, without a clear secular purpose. This was in direct response by the founders to the naming of the Church of England as the official religion of England and its colonies.
What clearer violation of this principle could there be than laws preventing gay marriage?
Think of it this way. Certain religions consider gay sex (and by extension gay marriage) to be a sin. Other religions do not, and in fact would be performing gay marriages today if they could. (And they do in Massachusetts and California.) Even though it may be the majority opinion that gay marriage is "wrong", that does not eliminate the protection of the First Amendment rights of those whose religious beliefs include sanctifying gay marriage.
And it is not just the establishment clause. The First Amendment also prevents our government from prohibiting free exercise of religion. When ministers are arrested for performing a religious ceremony (gay marriage), there is no doubt that this right has been infringed.
So, is there a secular purpose to banning gay marriage that can be used to overcome this objection?
What about the argument that limiting marriage to a man and a woman is best for children? That is a completely bogus argument. This is about marriage not about child rearing. If this were true, then gay marriage opponents should be working to ban gay adoption and gay artificial insemination. Indeed, many of the same people who are so worried about the children in this instance would not dream of imposing government will on parents to protect them in other instances where the science is more clear -- banning parents from smoking and drinking, banning parents from serving soft drinks to their kids, etc.
But the more fundamental reason that argument is flawed is that it is not equally applied. Many people marry and never have children or ever intend to (including me). Think of the elderly people that remarry long after child-bearing years. That's clearly not in the interest of the children they will never have, but we allow it anyway. But by the anti-gay marriage argument, all of our marriages should have been prevented because they will not result in children, the only valid reason for marriage.
Another argument that is often offered is to protect the word, the sanctity, or the tradition of marriage. Well, these arguments come perilously close to being explicitly religious in nature, which goes against our quest for a secular rationale. For what other word are we willing to sacrifice the rights of an entire class of citizens?
Plus, if you honestly check other cultures and traditions past and present, in this country and elsewhere in the world, you will find many other interpretations of the traditions around marriage, many of which are contrary to the beliefs of the majority here today. For example, in the Native American tradition, gays were accepted, even revered, and would often marry members of their own gender.
What about the concern that gay marriage is a threat to straight marriage? In what way? Nobody would be forced to marry anybody they don't want to, no church would be forced to perform gay marriages, and no existing marriages would be affected in any conceivable way. This argument loses me completely.
It is claimed that gays are trying to force their agenda on everyone else. But who is forcing anything on anybody? It seems to me that the people who are being prevented from marrying are the only ones being imposed upon.
Colorado is one of the states in which gays are explicitly prevented form marrying. It's now in the state constitution. It really makes me wonder how so many people can fail to understand something so clear as the First Amendment.