Oh please. Why does every critic of Theocracy think that the fact that there are more than one claimant to the title of "one true religion" by itself proves there is no such thing? I guess it does provide an excuse to be lazy and not to any investigating, however.
Western Civilization wouldn't be Western Civilization if we had based it upon the Priest Kings of ancient Israel; luckily they based it upon the most successful society that they were familiar with, the Romans; and it seems to have worked out pretty good so far - especially the part about elections for representatives who fulfill a limited government power for a limited time.
Wow, elections . . . what was I thinking of? Elections are a reason to get up out of bed every morning! No siree, no need for a Creator with an Ultimate Purpose when you can crusade for Limited Government (though you forgot the part about keeping your own money; that seems to be very important to rightwing atheists, though not to leftwing ones).
To answer your question, Mashiach will come and the Sanhedrion reestablished, probably with smaller bodies all over the world in union with it. The Divinely-commissioned authority will decide all these things (and no, I'm not going to be a member!).
Now blow me away with some ingenious argument like "oh yeah, the moslems think they're right too!" C'mon . . . you know you want to!
And I find tyranny scary, even if the tyrant claims to be ruling by God's law.
I am going to say this one more time and you are going to ignore it again because you have no answer to it: the laws already exist!!! Do you live in a "tyranny" because murder is a capital offense? Of course you don't. But it isn't the laws or penalties that scare you. For some reason it's the very idea that there is something more to them than the lowest social utility that gets you all up in arms.
You're more threatened by G-d's existence than by his rules (many of which you gladly submit to on the theory that they have their origin in "human reason").
Boy, now your a mind reader as well. I am a believer in God and the Bible.
The Bible has many laws. Who gets to interpret which get enforced and who gets to RULE? Razors creasing your flesh? Trimming the corners of your beard? Mixing meat and dairy? According to some this would mean outlawing surgery, barber shops, and pizza parlors. Who gets to decide? Who gets to rule? How do we organize Western Civilization while we are waiting for the Messiah to return? What about those that think he already returned? Death penalty for them?