Personally, I think that this elections most dangerous idea came from Mike Huckabee. Speaking to a Michigan audience, Huckabee exclaimed: "I have opponents in this race who do not want to change the Constitution. But I believe it's a lot easier to change the Constitution than it would be to change the word of the living God. And that's what we need to do -- to amend the Constitution so it's in God's standards rather than try to change God's standards so it lines up with some contemporary view."
Hands down, this is the most frightening and most dangerous idea to have been espoused by a candidate. Huckabee was literally saying that he would willingly alter the constitution crafted by the founders - which specifically, and intentioally, never uses the word "God" -- so that it might be "improved" by aligning it to the "will of God."
The potentiality of this statement is devastating and, if fulfilled, would negate one of the most important and unique features of the US political system: a separation between church and state.
I honestly can't imagine any specific policy measure offered by any candidate that would have more dasterdly reourcussions than to subvert the constitution and the principles on which America was founded.