Those people who believe this and aren't just outlandishly bigoted believe so because as Christians they do not have either the experience or lack of privilege to really understand the repercussions. People with privilege are prone to viewing discrimination through the "worst of the worst" lens. That means that the thousands of microaggressions that religious minorities are subject to are almost entirely invisible to Christians, and when they're pointed out they aren't registered as religious discrimination.
My father is a prime example of this attitude. He's politically conservative and although he's not religious (he may even be agnostic), he was raised in a conservative Lutheran family and so that's what he considers himself. Some of the most heated arguments I've had with him have been over the subject of government-sponsored religious displays such as nativity scenes. Even though he knows I am not Christian and is perfectly fine with that, he still has it very firmly implanted in his head that these scenes have some sort of universal appeal and that non-Christians should just learn to live with them. So far no amount of verbalizing the experiences I've had as a non-Christian has convinced him that there's anything wrong with that.
I personally feel many of the people who support something as offensive as a State religion are picturing this sort of culture... one where people are allowed to be any religion, but where Christian symbols, prayers, holidays, and stories predominate in religious and social functions without the threat of legal intervention. In short, what they're looking for is the ability to continue being privileged, not an actual theocracy.
And you know what? That's so much more fucking dangerous! The reason it's more dangerous is because they're talking institutionalizing a set of microaggressions and symbolic actions rather than something people of privilege would really recognize as discrimination. Think about the following privileges Christians already have:
- Saying "Merry Christmas" is considered a generic holiday greeting whereas any other specific holiday greeting comes off as awkward at best.
- "Non-denominational" prayers for secular events are usually written with Christians in mind. When explicitly non-Christian prayers are performed, they are usually more controversial.
- Christians are the only group in which one of their holidays was declared a federal holiday.
- People are constantly fighting to put Christian symbols on public or government property, and often winning those fights.
- It's not considered socially unacceptable in most contexts to use Christian-based greetings or statements like "God bless you," "this tastes like heaven," "I pray to God...," "I'll pray for you," and so on.
- People are likely to be able to wear Christian symbols and apparel at work or school without being asked to hide them or take them off.
- It is relatively easy to find Christian places of worship as well as services that aren't specifically religious (banks, hospitals, schools) which are explicitly run using Christian ideals.
- Christians usually have access to television and radio stations without purchasing extra services.
- Organizations like the Boy Scouts--which is not a Christian organization--can get away with discrimination by implying that Christian beliefs are universal.
To me, that's what's so scary about this. A lot of the work I do trying to dismantle Christian privilege is derailed by people who do not recognize the pervasive ways their faith is elevated and privileged in society. I've seen many a self-identified religiously tolerant person see absolutely no problem with putting a ten commandments monument on government property. That's scarier than the full-on forced theocracy most people are picturing because there's an extent to which it's already happening.
Which is, incidentally, why this sort of thing is such a big issue now... non-Christians are finally asserting ourselves as worthy of the same respect as Christianity, and so people who are accustomed to that privilege are trying to push us back as we make those advances. We can't let them.