First of all, this project has absolutely nothing to do with freedom of religion, and those making that argument can be disregarded as hopelessly ignorant. Next, this project is a monument to the terrorists of 911. Radicalized Muslims have seized an opportunity to rub our noses in their hatred of the USA. The WTC represented commerce, wealth and openness. A mosque at ground zero will be symbolic proof that Islam is defeating freedom. The Muslims know it, but there are millions of stupid Americans who think acquiescing to and appeasing the people who hate us will make them love us. Last, a mosque at ground zero will be moral victory for liberals who hate conservatives and patriotic Americans who love this country. It is a statement that we wronged Islam, and this is our way of making up for it.
Islam has nothing to do with religion. It is a complete, totalitarian political and economic system with a religious veneer to make it more palatable (and more oppressive) to those it is conquering.