First is Christianity a theocracy friend belief? This isn't arguing that their haven't been Christian theocracies, but is the belief structure friendly to a theocracy
From the start according to the bible
God pretty much ran his chosen people lives, with one person acting who was Gods representative to rule on how Gods chosen were following Gods law. This changed during Moses time.
Gods people multiplied and it was agreed with Gods approval that underlings would judge the easier cases and the harder cases would be brought to Moses.
Exodus 18 (King James Version as is most all or all citations here)
13 And it came to pass on the morrow, that Moses sat to judge the people: and the people stood by Moses from the morning unto the evening.
14 And when Moses' father in law saw all that he did to the people, he said, What is this thing that thou doest to the people? why sittest thou thyself alone, and all the people stand by thee from morning unto even?
It was finally suggested and Moses did appoint helpers to handle the lesser cases.
Soon the people wanted regular King to rule over them. Though God was not happy, but agreed.
1 Samuel 8 (King James Version)
4 Then all the elders of Israel gathered themselves together, and came to Samuel unto Ramah,
5 And said unto him, Behold, thou art old, and thy sons walk not in thy ways: now make us a king to judge us like all the nations.
6 But the thing displeased Samuel, when they said, Give us a king to judge us. And Samuel prayed unto the LORD.
7 And the LORD said unto Samuel, Hearken unto the voice of the people in all that they say unto thee: for they have not rejected thee, but they have rejected me, that I should not reign over them.