The concerns of some in the religious right about Romney's Mormonism are just the tip of the iceberg. Today the evangelicals, Catholics, orthodox Jews, Mormons, etc. have an uneasy alliance as they battle some of their hot-button common enemies such as gay marriage and abortion. But if these strange bedfellows get much further in their attempts to legislate their religious beliefs, they will probably not like what they see as their differences come into focus.
How will a moderate evangelical respond to Catholic legislation disallowing birth control? How will a Catholic respond to Biblical literalism taught as "science" or "history" in the classroom? What prayers will they pray in public school? And so on. Those in minority religions, in particular, should watch their backs.
The wall of separation between church and state protects the religious as well as the secular. The religious right weakens that wall at its own peril.