this is somewhat related to that 'mosque two city blocks from ground zero' argument.
Most of the people against it - far right constitutionalists - are actually supporting a suppression of the Constitution in this case. Freedom of religion, like it or not. What distance is 'acceptable' to put a mosque in NYC from ground zero, and where is this distance in the constitution?
As offensive as some might find it, the Constitution would say they have the freedom to put that mosque there. It would be anti-american to tell ANY church "You have to be 10 or 20 blocks from this or that"...
The people who are against it know they have the right to build one there. It has more to do with the question, "Why there?" Why, of all places, do they need to put a mosque at the place where the religion that the mosque represents killed 3,000+ people?
Even the Washington Post, liberal rag that it is, has come out and said it's not right to put one there. Mosques are built as a sign of Islamic supremacism (hence why thousands have been built over churches, temples and other houses of worship) and this mosque is a perfect example of that. Rubbing it in our faces after they've already killed 3,000+ people.
And while the mosque is a bad idea, the major problem is the guy leading the building of it, a man who is on paper calling for the establishment of Sharia Law in America, refuses to denounce terrorism, is not in favor of inter-faith dialogue, has ties to the Muslim Brotherhood, refuses to say where the financing for this $100m project is coming from (he says from American donors in English and then says it will be foreign funded in Arabic) and so and so on. His wife says that this center will help non-Muslims integrate (not the other way around). Integrate into what? Sharia Law.
It's just ridiculously distasteful, even down to the name of the project. And polling shows that Americans are against it by a 2:1 margin.