Long before G-d "changed His mind" and started a new "one true religion" there was already a "one true religion." That religion was, is, and always shall be TORAH. This means the 613 Commandments for Jews and the Seven Commandments for non-Jews (and I am among the latter, not the former). In that religion there was no "J*sus prayer" by which one "passed from nature to grace." There was just the One True G-d, the G-d of Genesis, Who created he universe and has absolute sovereignty over everything in it. This G-d gave a system of Laws to mankind and declared He would grant rewards for obeying Him and mete out punishment for disobeying Him. However complex it is in practice (and it is much more complicated than most people realize), it is in concept the ultimate in simplicity. Perhaps you find our laws against murder an onerous forcing of religion on the private conscience? Why don't you launch a moral crusade to repeal them???
Have you ever read a Bible in your life? When was Moses "saved?" When was Joshua "saved?" When were any of the Biblical Jews "saved??????" When, in the only government G-d has ever established on this earth, was there ever "separation of church(?) and state?" It is literally amazing how radically different the religion of the Bible is from the religion that now claims to be the one true Biblical religion!
Have you ever read the Book of Joshua? Or the historical books that tell of Israel at her glory when the Holy Temple stood and she was ruled by G-d's anointed king? Where was the "separation of church(?) and state" while all this was going on???
Let me go on record as stating that the Ten Commandments actually only apply to Jews, not to non-Jews. Non-Jews are bound by the Seven Commandments of the Sons of Noah and it would be much more appropriate for them to be enshrined in our institutions. However, most people are unaware of this and the Ten Commandments are so associated with the True G-d (plus non-Jewish humanity has historically taken upon itself such Jewish commandments as honoring father and mother) that this distinction is currently meaningless to the masses. And it's also important that the Bible-thumping heartland maintain this very important link to `Am Yisra'el.
I suggest you read your Bible again (and start at the front this time please!) and see just how alien the individual, voluntarist religion you advocate is to the Bible. After that, I suggest you visit my web site.
The modern notion of "separation of Church and State" is indeed nonsense, and the sooner we drop this idiotic notion that there must *never* be any established religion, we'll be better off. Separation has led to an acrimonious divorce.
As far as the Davidic kingdom goes, it was less the culmination of God's great plan for the Hebrews, than a concession to their stubborness (cf. 1 Samuel 8)--
8:7. And the Lord said to Samuel: Hearken to the voice of the people in all that they say to thee. For they have not rejected thee, but me, that I should not reign over them.
8:18. And you shall cry out in that day from the face of the king, whom you have chosen to yourselves: and the Lord will not hear you in that day, because you desired unto yourselves a king.