Let's say the mosque (you know what mosque) gets built, as it certainly might, public opinion notwithstanding. What's the next theological concession America's Christian churches get to make in the name of brotherhood, sisterhood, pluralism, world peace and amity, the reconstruction of America's image, etc., etc.?
First it's one thing, then another: public observances of religious holidays, memorial crosses on public lands, atheist authors on the attack, affronts galore to Christian morality as understood for even longer than Richard Dawkins has been on the scene. Prayer in schools? Lost that battle long ago, toward the end of a different age for American Christianity, when the general assumption was that a brief word to the Almighty, even spoken in public places, wasn't a bad idea.
The Christian consensus that supposedly dominated American life half a century ago hasn't dominated anything for years. Only the gay marriage foofaraw, which centers on how to define marriage -- the church's way or The New York Times' -- affords secular pundits a good workout these days. Oh -- and priestly sexual abuse, which some media accounts could lead you to see as the modern church's primary activity.
On the left, the mosque proposal gets two thumbs way up -- in Siskel/Ebert parlance -- because at least one of those thumbs can be seen as gouging the "religious right." The other thumb points us to the wonderful world of religious indifference. Yawn. Mosque, church, synagogue, who cares? Just the same old story told different ways, with different legends, none mattering more than another.
The general comparability of all religions is the narrative that informs support for the New York City mosque -- as, to tell the truth, it informs support for the mosques now springing up through once-Christian Europe. The necessity of throwing back that narrative isn't the only reason most Americans reject the idea of admitting Islamic symbols and practice to the neighborhood of the 9/11 outrage. It's a reason that works, even so.
A Muslim need not believe in the truth of Christianity, but secular commitment to "diversity" -- a commitment certain oddball bishops and theologians appear to support -- undermines the American understanding of national identity. You can lay aside or leave open special "truth" claims if you like. Where on earth do claims to liberty under law arise if not from the heavily plowed ground of Christian belief concerning man -- and, as we would add nowadays, woman -- as the special creation of God, worthy of protection against tyranny, oppression and other awful incidents of existence? No God -- no Christian God at any event -- no liberty, no freedom, no personhood, is the rule of thumb.