[Neophyte]

But when Christians oppose gay marriage because of "God's Will," "God's nature," or the "Bible says so." Like it or not that's an attempt at theoracy.

With all due respect, I cannot agree. Theocracy is such an arrangement of society when both the legislative and the executive functions of the state are conducted by the religious hierarchy. Just that.

When Christians reject gay marriage, it's because such institution contradicts the tenets of their creed. If it so happened that the given Christian, but not theocratic country, had a government stupid enough to introduce gay marriage through the law, the Christians would be very unhappy but powerless to stop it.

[Hong Kong Expat]

What you are missing is when a Christian says "It's God's Will" it cuts off all debate and rational arguments.

For example, if somebody did a study and found that Gay Marriage reduced pedophile by 85%, AIDS by 50% and Drug Use by 20%, Christians would still be against Gay Marriage because of "God's Will."

Theocracy in the broad sense of the word is to use the secular law to impose religious norms. You have the Muslim countries at one extreme and you have blue laws at the other.