Just because someone emphasizes the importance of keeping the Ten Commandments of God, it doesn't mean he or she is in bondage to a salvation by works theology.
The nonsense of accusing people of being legalistic for being in favor of keeping God's Ten Commandments, needs to stop.
Instead of jumping to conclusions about that person's relationship with God, ask questions for clarification.
Yes, we are saved by grace through faith, not by works (Eph. 2:8-9); but let's not forget that we were created for good works (v. 10).
When I look at God's Ten Commandments I see something good, not evil.
It is a bit complicated to explain.
Core commandments (such as the 10 commandments) can be law or can be just as the term itself reflects, that is, commandments. Whether they have the law effect will depend on which covenant they are in.
First covenant,
Granted with - Noah
Coverage - all mankind
Born with - yes
Jewish covenant,
Granted with - Moses
Coverage - Jews
Born with - yes
New Covenant,
Granted with - Jesus
Coverage - all mankind
Born with - no
The covenant bound with gentiles should be based off the covenant with Noah, which basically says that humans need to abide by the "Law in Hearts". "Law in Hearts" is basically our conscience. We need to follow our conscience to act. However, our conscience may shift when our heart is hardened. God wrote the laws in our hearts for us to act righteously to be saved. However, this set of law can be blurred out by our hardened hearts as time goes by. An example can be that, homosexuality was widely rejected tens of years ago but widely accepted today. So is nudity. That's how our hearts are hardened to fail to see what God requires us to do by writing laws as our conscience.
Thus God gives a black and white set of laws to the Jews. It can thus be kept intact even when one's heart is hardened. That's why even Jesus said that the Jews should listen to what the Pharisees said but just don't follow what they did. It is because the set of laws (Mosaic Law) is well kept contextually but failed to observed by the Pharisees with their hearts hardened.
Even when Mosaic Law is put in effect through Moses, it by no means says that the Jews don't need to follow their conscience to act. This is the overlapping effect of law and covenants. For the same reason, Law and covenants will not go away as it's not necessary for them to go away. What has been adjusted, technically speaking, is which standard is used for one's final judgment. Thus the gentiles will be judged by the "Law in Hearts" while the Jews will be judged by Mosaic Law (i.e., the covenant with Moses to be more precise).
When the New Covenant is put in effect, and due to the same overlapping effect, both the Jews and gentiles still need to follow their conscience to act (first covenant), with the Jews need to follow the Mosaic Law to act. Even the rites don't formally go away. However, today's Jews can't do rites acceptably to God ever since the tabernacle was destroyed in AD 70. They thus cannot perform atonement offerings inside the tabernacle and through the priests. It signifies that only Jesus can save under the New Covenant era, theologically speaking.
Core commandments are completely something else. Core commandments can exist in each and everything covenant. Don't kill, don't steal and etc. are common sense to our conscience. However we are not sure whether loving God is part of Law in the first covenant. Law means that if you break one you break all and you are pretty much dead after breaking it. In the covenant with Moses, the 10 commandments are part of the Law applicable to the Jews. This is the case even in modern society. If you break a formal law you go to jail. If you break some traffic ordinance you can walk away by paying the penalty in the form of money. You can rush the red traffic light as many time as you wish without going to jail. It however by no means says that you don't need to follow traffic lights to drive.
Jesus has mentioned all of the 10 commandments except of the Sabbath. The significance is that it means that those commandments are still the core commandments in the New Covenant. However, they don't act as Law but commandments in terms of our final judgment. That's why even a killer can repent to be saved. However it by no means says that you can murder at will or break them willfully as you wish. In the end, it's all up to Jesus to judge. While He said that the "O Lord" in your mouth will not save you if you are an evil doer in His eyes.
So we do need to observe the 10 commandments. As for Sabbath, Christians attend Sunday services as our Sabbath. All mankind observe the Sabbath as Sunday is lawful rest day for all humans. The significance is that all humans are living under God's sovereignty.
That said. The older covenants are in effect all the times as the New Covenant is not a born with covenant. Everyone is bound with a default covenant when we were born. A Jew is a Jew if he is circumcised since the 8th day of birth. Or else he's not a Jews in terms of Law and covenant even he's a Jew of bloodline. If he continues to want to be a Jew, he needs to abide by the Mosaic Law, or else he's a gentile. Gentiles are bound with an earlier covenant when born where they will be judged by the "Law in Hearts". This how they will be judged until they choose the New Covenant with consent. With the New Covenant, they both will be judged by faith instead of Law.
