Oh absolutely. It would have to retain a purely voluntary
   status. But of course, theocracies are always possible unless
   the laws of the State are strong enough to forbid it.... and
   there's no revolution to overturn constitutions. Then again,
   even in "milder" theocracies that are primarily democratic in
   government, there's enough secular elements for a viable
   society. Still, I prefer a freedom-of-religion without state
   control but that's mostly because I was raised in a culture
   promoting it as a value, so it's hard to be totally objective.