In Matthew 4:15-23, Jesus began his ministry with the Gospel message to repent for the Kingdom of God is at hand, which was a light to the Gentiles, and the Law of Moses was how his audience knew what sin is (Romans 3:20), so repenting from our disobedience to it is a central part of the Gospel of the Kingdom/Grace, which Paul also taught based on the Law of Moses:Does Grace replace the law?
The kingdom gospel that Jesus presented the nation of Israel with was integral with the law.
Mat_5:17 Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.
Acts 14:21-22 When they had preached the gospel to that city and had made many disciples, they returned to Lystra and to Iconium and to Antioch, 22strengthening the souls of the disciples, encouraging them to continue in the faith, and saying that through many tribulations we must enter the kingdom of God.
Acts 20:24-25 But I do not account my life of any value nor as precious to myself, if only I may finish my course and the ministry that I received from the Lord Jesus, to testify to the gospel of the grace of God. 25 And now, behold, I know that none of you among whom I have gone about proclaiming the kingdom will see my face again.
Acts 28:23 When they had appointed a day for him, they came to him at his lodging in greater numbers. From morning till evening he expounded to them, testifying to the kingdom of God and trying to convince them about Jesus both from the Law of Moses and from the Prophets.
In Romans 7, Paul said that the Law of God is good, that he wanted to do good, that he delighted in obeying it, and that h served it with his mind in contrast with the law of sin, which was working within his members to cause him not to do the good that he wanted to do, which was waging war with the law of his mind, which held him captive, and which he served with his flesh. In Romans 8:1-7, Paul said that the Law of the Spirit of Life has freed us from the law of sin and death, that Jesus set us free from the law of sin so that we might be free to obey the Law of God, and he contrasted those who walk in the Spirit with those who have minds set on the flesh who are enemies of God who refuse to submit to the Law of God.However, the gospel of grace for the gentiles was not based on the law;
Gal_5:18 But if ye be led of the Spirit, ye are not under the law.
In Galatians 5:14, Paul spoke in favor of obeying the command to love our neighbor as ourselves, which is one of the greatest two commandments of the Law of God. In Galatians 5:15-23, Paul contrasted the desires of the flesh with the desires of the Spirit and everything that he listed as works of the flesh that are against the Spirit are also against the Law of God while all of the fruits of the Spirit are in accordance with it, such as with love being one of the fruits of the Spirit. The desires of the flesh causing us not to do the good that we want to do is how Paul described his struggle with the law of sin in Romans 7-8, so that is the law that we have been free from by the Law of the Spirit and are not under when we are led by the Spirit. The Law of God was given by God and the Spirit is God, so it would be contradictory to interpret Galatians 5:18 as referring to the Law of God as if we are not led by God when we are led by God.
The New Covenant was only made with the house of Judah and the house of Israel (Jeremiah 31:33), so it is only through becoming joined to Israel through faith in Christ that Gentiles are able to partake of the New Covenant. In Ephesians 2:12-19, Gentiles were at one time separated from Christ, alienated from Israel and strangers to the covenants of promise, having no hope and without God in this world, which is in accordance with Genie's at one time not being doers of the Law of God, but through faith in Christ all of that is no longer true in that Gentiles are no longer strangers or aliens but are fellow citizens of Israel along with the saints in the household of God, which is in accordance with Gentiles becoming doers of the Law of God.The new covenant Jesus established is the absolute fulfillment of the written law.
The old covenant at Sinai was offered by God and accepted by the nation of Israel. The new covenant was for Israel and offered by Jesus, but not accepted by Israel. The new covenant will be established when the faithful remnant of Israel accepts the offer at the end of the tribulation.
Today there is no covenantal agreement between God and humanity. We simply have the offer of grace to all who trust in Jesus. This should inspire a heart of gratitude.
Eph 2:12 That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:
Eph 2:13 But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ.