Should Muslims be allowed to build a mosque at Ground Zero? Merely posing the question is an act of deliberate distortion. As its defenders point out, the Community Center at Park51 will occupy not a solitary inch of the 16-block site on which the Twin Towers stood. Once built, the center will indeed house a mosque, "open and accessible to all" — but also a swimming pool, basketball court, auditorium, library, day care, restaurant and cooking school. The center is being built by a private organization on land it legally owns. Twenty-nine out of 30 Lower Manhattan community board members...