First off i want to say that the people who are building this mosque are not only Muslim, but they are American too.
What if Germans decided that they would not allow any Christian churches to be built near any land that Hitler utilized during the holocost because he was a Christian.
There is a need for a new mosque because in that tri-state area there are over 1 millon muslim-americans, and their old building cannot possibally hold all of them. they need more space. Muslim-Americans have been worshipping on this ground that the mosque will be built on for a few years now, just without the title of a mosque. Think about it, its new york city, are there really THAT many places where they can build their own building?
The muslim-Americans who are going to build this mosque and the people who attend the current one and also utilize the new one have accepted people of different religions to sit in on their services, not to try to get them to become muslim, but to show that they are not so different. They also plan to carry this over to the new building, yes this will mainly be for Muslim-Americans, but they are not going to throw out anyone who is not their faith.
Muslim and Christianity (no im not implying that all Americans are Christian, but it is a predominate faith in this country) are not too different with the basic sense of their religion. People who are muslim believe in one god, as do christians, the only difference is that muslims don't believe that Jesus was the son of God, but a messenger sent by god because there is no one like him. Which yes it is a difference, but it really isn't that far fetched.
I really believe that building a mosque 2 blocks away from ground zero should not be a problem, the people using this building are not the ones who were behind the terroist attack. Merely people the same religion/culture. Peope of most faiths have others that follow that faith who have done something horrible such as mass murder, so if a murderer was Christian, would that mean just because i am christian I would do the same thing? No. Or heres another one, many murderers have very high intelligence, so that means anyone who is super smart is going to go kill someone..... Uh, yeah right.