Muslim American citizens have a constitutional right to build a religious and cultural center anywhere in this country that Christians or Jews may build one. This is so clear and obvious that opponents of the planned Muslim center near Ground Zero usually concede or avoid the point. Then they say that the center should not be built at this location anyway. I guess they mean that these Muslims should give up their right voluntarily--or under duress.
And why do they say this? Well, the two obvious possibilities are bigotry and political opportunism. Maybe they associate this Muslim center with the perpetrators of 9/11. That would be bigotry, since the only real connection is that both are Islamic. Or maybe, in the case of Republican politicians and right-wing commentators, it is simply a matter of taking advantage of a political opportunity that has fallen into their laps.
Both of these reasons are fairly unattractive. Is there any reason to oppose the mosque that isn't bigoted, or demagogic, or unconstitutional? None that I've heard or read.
Republican Rep. Peter King said on CNN yesterday that "the issue is not that there's a legal right to build the mosque, but that those involved should listen to public opinion, which is strongly opposed to the project." But the whole point of the First Amendment is that the freedoms it guarantees are not constrained by public opinion. You don't need a Bill of Rights to protect people's right to do or say things that are popular. The First Amendment would be of limited value if every exercise of freedom that wins its protection immediately faces the second hurdle of a popularity contest.