"Priest Calls Vote for Obama a Mortal Sin."

Given that was said in a letter to parishioners and in his official capacity it sure looks as if the good priest has crossed a line. And is advocating for a theocracy in the US, in violation of the Constitution. Seems a blatant attempt to influence the political process of all Americans for religious reasons.

As tax-exempt status is available only to those organizations which do not seek to cross the church - state line, I think his parish should lose it's tax-exempt status forthwith.

A counter argument can be made that the government interfered with religion in it's hassles with Mormons and later with Mormon breakaway groups on the polygamy issue. That's a blatant attempt to impose secular values on a religion.