The validity of my question pertains to the concept that the 10 commandments was valid for the nation of Israel under the old covenant, and that has not changed in the new covenant per many in Christianity/Messianic Judaism. So how did this concept continue to formulate the church's view on the 10 as applicable since the first century? If the 10 were given to Israel, as part of their covenant with God, then where is the leap into the new covenant which is, as you point out, neither Jew or Gentile aka one new man, a new foundation built upon Jesus Christ as the Head Corner Stone and New High Priest, the apostles, and prophets --- not the Law/Covenant of Moses/Levitical Priesthood?
There is no leap that Christianity is the Ten Commandments. The New Testament is clear the law, for the Christian, is the law of love of God and fellow man, and this the basis of all moral law, Matthew 7:12, Matthew 22:36-40. You don't really need the Ten Commandments to be a moral person, led of the Spirit, as you'll not violate moral law, if you are obedient to the Spirit and of a righteous inner man. Law is primarily needed for law breakers, in the first place. I know I don't need a list to tell me it's not righteous to murder, steal, lie, covet, adulter, do a veritable much longer list of things of the flesh I'd not want to be a victim of, as a matter of fact, the Ten Commandments even only some biggies and a starting point that keeping, of themselves, can make nobody truly righteous, truly loving in an agape fashion, at all.
I would make the case, though, because the New Testament Bible states, that setting aside a day of the week as a sabbath, by commandment, like your Adventist/Jewish Saturday, is spelled-out in the New Testament as unnecessary. If one esteems every day alike, we have that privilege and freedom, therefore that leaves nine commandments that would constitute a moral breach, not ten, re: Romans 14:5, Colossians 2:16-17. In every instance of legalism creeping into Christianity, you'll find cult status.
The Ten Commandments is much overrated, in terms of anything comprehensive of the sin nature, given the Lord Jesus said bad thought is murder and adultery, harboring hate and lust in your heart guilty of these same, scripture also clear breaking one commandment is breaking the whole law. The Ten Commandments may help keep a lot of people out of jail, but not out of hell, and the gospel of Jesus Christ, as mentioned, is quite expansive of what comprises sin that no law keeper has scratched much more than the surface of.
Of course, if there's anything saving in the law, you wouldn't need grace, and Jesus Christ would have died for nothing, Galatians 2:21.
