So why are there people who call themselves Christians who want to make the US a theocracy? The people that those vote for enact incredibly harmful policies in the name of religious morality
A theocracy is a political system in which religious leaders have formal control over the state, and the state directly favours the doctrines of a particular established religious sect–it is standard in a theocracy for the head of state to be a cleric (bishop, mullah, ayatollah, lama, etc). Among internationally recognised sovereign states, there are only three contemporary examples of theocracies – Afghanistan (whose de facto head of state is the Supreme Leader of the Taliban, Hibatullah Akhundzada, an Islamic scholar); Iran (whose head of state is its Supreme Leader, Ayatollah Ali Khamenei); and Vatican City (whose head of state is, of course, the Pope). I'm not aware of any significant movement advocating the adoption of such a political system in the United States.