It doesn't matter who is president, America cannot be made into a theocracy. Our Constitution guarantees that government cannot have a state sponsored religion. This isn't really a danger, it is used as a scare tactic, but it is highly unlikely.
Socialism, fascism, and even corporatism are much more of a danger to our country. The problem is that the Democratic and Republican parties are more than willing to bring us in these directions. Our politicians are lobbied at all day long by people who are payed big money by corporations to get laws passed in their favor.
Joe Biden's, Obama's vp pick, son just resigned from his job as a Washington lobbyist a couple of days ago. I would be willing to wager that Mr. Biden has voted for everything that his son lobbied for.
The system is crooked, because it is infused with money, and the answer to this problem does not lie with Obama or McCain, Democrats or Republicans. The answer lies in the people taking their governmet back from these crooks in Washington, and unfortunately this is not likely to happen until such time as things start to get very uncomfortable for the American citizen.
Regardless, the real danger is not from just one party, and the solutions do not lie within the other party. This is a lie fed to us by the media (which is owned by the corporations that you are rightfully fearful of) to benefit the system.