Acceptable?

Why is it that Christianity is the only acceptable religion in the United States? It seems that any other religious belief is completely and totally ostracized from the public view. Regardless of what your personal beliefs are, in a society that bases a huge amount of its self-worth on ideals of "freedom," religious or otherwise, does anyone honestly think that a public affirmation of faith that is different from our western Christian one would be as readily accepted?

Case in point, while attending a graduation the other day I came across something like this. The final speaker of the night, while thanking those around her, gave a final and thoughtful thanks to "God." It struck me as weird that no one seemed to think that her statements were unacceptable, and I even heard some "amens" through the crowd. Obviously she was talking about the Christian God, I hardly doubt she was referencing the "God of the Philosophers," a sort of abstract notion of a religious being, and it made me wonder whether or not her statements would have been as readily accepted if she would have referenced another religious view point. If someone would have said "praise be to Allah" I think there would have been some discontent, at the least, and maybe even a downright upheaval.

I'm not promoting any religion over another, nor am I trying to be some kind of cool non-religious person. I do think that religion does, and probably should, play a meaningful role in everyone's life. What I am saying, however, is that in a society that's making an attempt to be as non-judgmental as possible, which I think is the overwhelming majority despite "Tea Party" idiots, should one religious preference be more acceptable than any other?