I wanted to spend more time on this but hopefully it makes sense.
Let me respond for now by asking you another question...
Just what (in your view) is the law of Christ and in what way is it different than the Law of Moses?
Please answer with Galatians 3:21 in mind.
This is my current understanding. The OT is full of things that we can look to for a better understanding of the Christian age. If we look at the Law of Moses, it can be broken down into two basic parts. Man’s relationship with God and his fellow man. I believe the Law of Christ is the same relating to our relationship to God and man. The LOM goes into detail what is sin against God and man. The particulars don’t apply any longer as well other particulars of the LOM, hence our liberty but the essence of them does, love God and your neighbor.
The LOM goes into detail on what was to be done about sin. I believe it’s the same under the LOC, the details are different but the basics are the same. In Christ we can and do sin against God and man but instead of using animal sacrifices we have a perfect sacrifice that is able to forgive sins. The serious sins could not be atoned and God wanted the evil removed so they were cut off or put to death. In Christ they can be forgiven but they cannot continue. For example:
Lev. 20:11
If there is a man who lies with his father's wife, he has uncovered his father's nakedness; both of them shall surely be put to death, their bloodguiltiness is upon them.
We see the same situation in the NT.
1 Cor. 5:1
It is actually reported that there is immorality among you, and immorality of such a kind as does not exist even among the Gentiles, that someone has his father's wife.
Paul said get him out so that his soul may be saved.
5
I have decided to deliver such a one to Satan for the destruction of his flesh, so that his spirit may be saved in the day of the Lord Jesus.
We know from the next letter that he did seek forgiveness and returned.
I could go on, but there are a lot of principles we can learn and I believe can be applied to the LOC.
Gal. 3:21
Is the law, therefore, opposed to the promises of God? Absolutely not! For if a law had been given that could impart life, then righteousness would certainly have come by the law.
The way I understand it, LOM was not intended to replace the promise, if it were then inheritance (righteousness) would have been based on it. It had a purpose but it wasn’t what was promised, we received the promise and it's far better.
Heb. 11:39
And all these, having gained approval through their faith, did not receive what was promised, 40 because God had provided something better for us, so that apart from us they would not be made perfect.