The Gentile-Christians took the helm of the church and made the Lord's Day Sunday the weekly day of worship.
The meeting in Chapter 15 of Acts and the letter issued by James made it clear that the Gentile-Christians were not going to be following Mosaic Laws. And Paul made it clear that Gentile-Christians are not under the Law
No one has the authority to change God's commands or to countermand them. I don't think that it makes sense to interpret the Jerusalem Council as ruling that follower of Christ shouldn't follow over 99% of what he taught and even less sense to think that is what they ruled and then to think that we should follow the Jerusalem Council instead of Christ. Either Acts 15:19-21 contains an exhaustive list for mature believes or it does not, so it would be contradictory to treat it as being an exhaustive list in order to limit which laws Gentiles should follow while also treating it as being an non-exhaustive list by taking the position that there are obviously other laws that Gentiles should follow. It was not given as an exhaustive list for mature believers but as a list intended to avoid making things too difficult for new believers, which they excused by saying that they would continue to learn how to obey Moses by hearing him taught every Sabbath in the synagogues.
The fact that the Law of God brings death to those who refuse to submit to it is not a very good reason for refusing to submit to it.
In Deuteronomy 28, it describes the blessing of the Law for lawfulness and the curse of the law for lawlessness, so being redeemed from the curse of the law is setting us free to enjoy the blessing of lawfulness. In Titus 2:14, it does not say that Jesus gave himself to redeem us from the Law of Moses but in order to redeem us from all lawlessness and to purify for himself a people of his own possession who are zealous for doing good works, so the way to believe in what he accomplished through the cross is by becoming zealous for doing good works in obedience to the Law of Moses (Acts 21:20)
The Spirit has been given to those who obey God (Acts 5:32), so while it is true that we can't earn the Spirit as the result of our obedience to God, that does not mean that we are not required to obey Him.
God wanted His children to repent and to return to obedience to His law all throughout the Bible and even Jesus began his ministry with that Gospel message (Matthew 4:15-23), so it would be absurd to interpret Galatians 5:4 as Paul warning against obeying God and saying that we will be cut off from Christ if we believe the Gospel of Christ. In Psalm 119:29, he wanted God to be gracious to him by teaching him to obey the Law of Moses, so that is what it means to be under grace and it would be absurd to think that he wanted God to be gracious to him by teaching him how to fall from grace.
Paul equated the Law of God with the law of Christ by saying in a parallel statement that he was not outside the Law of God but under the Law of Christ.
The fact that the Law of God brings wrath for those who refuse to submit to it is not a very good reason for refusing to submit to it.
Romans 6:14-15
Romans 8:2
Romans 7:6
Romans 7:8
In Romans 5-8, Paul described the Law of God as being something that is the good that he wanted to do in contrast with describing the law of sin as being something that was causing him not to do the good that he wanted to do. In Romans 6:14, Paul described the law that we are not under as being a law where sin had dominion over us, which clearly does not describe the good that he wanted to do, but rather that is the role of the law of sin. In Romans 7:22-23, Paul said that he delighted in obeying the Law of God in contrast with saying that the law of sin held him captive, and it would be absurd to interpret Romans 7:6 as if Paul delighted in being held captive to sin, but rather that is the role of the law of sin. In Romans 7:25-8:2, Paul said that he served the Law of God with his mind in contrast with saying that he served the law of sin with his flesh and he said that the Law of the Spirit has freed us from the law of sin and death, so the law of sin and death does not refer to the Law of God. Romans 7:8, It is the law of sin that took the opportunity through the Law of God to cause coveting to increase and sin would be dead apart from the law of sin causing us to sin.
Changing the medium upon which the Law of God is written from stone to our hearts does not change the content of what it instructs us to do. For example, the command to keep the Sabbath holy written on stone has the same content as the command to keep the Sabbath holy written on our hearts.
Galatians 4:21
Galatians 3:10
According to Deuteronomy 27-30, the way to be blesses is by relying on the Law of God while the way to be cursed is by not relying on it, so it would be absurd to interpret Paul as quoting from that passage in order to support a point that is arguing the opposite of that passage. The fact that cursed is everyone who does not continue to do everything in the Book of the Law means that we should continue to do everything it it in order to avoid being cursed, which is why those who rely on works of the law instead come under that curse.
Someone who disregarded everything that their tutor taught them after the purpose of a tutor has been fulfilled would be missing the whole point of a tutor.
In Galatians 5:16-23, 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. 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 5-8. In Romans 8:2-8:7, Paul said that the Law of the Spirit has freed us from the law of sin and death and he contrasted those who walk in the Spirit with those who have minds set on the flesh who are enemies of God, so the law that we are not under when we are led by the Spirit is the law of sin and death, not the Law of God. The Law of Moses 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 Moses as if we are not led by God when we are led by God.
The Law of God was never given as a way of earning our justification even as the result of having perfect obedience, which makes it that much more true that we can't earn our justification as the result of obeying works of the law.
Again, the Law of God was never given as a way of earning our righteousness. However, if someone returns to the lawlessness that Christ gave himself to redeem us from (Titus 2:14), then that would also be treating Christ as if he died for nothing.
In Hebrews 8:10, the New Covenant still involve following the Law of Moses, so the Mosaic Covenant becoming obsolete does not mean that we should not continue to obey the Law of Moses.
If you agree that it is by the Law of Moses that we have knowledge of what sin and that we should refrain from doing what God has revealed to be sin, then you should agree that we should obey it.
Not only are we not under the Old Testament Laws, the concept of Law is gone. The Mosaic Law was made up of 613 Laws, but still it was not enough to cover all the possible sins. If you broke one, you broke all of them and there was no forgiveness. Yeshua's teaching is matter of heart and mind, love God and love one another and do no wrong. In the New Covenant our sins are between us and Yeshua and if we confess our sins He if faithful to forgive us.
The fact that the Law of Moses does not list every possible sin does not mean that we should not refrain from doing the things that is does reveal to be sin. In James 2:1-11, he did not say anything about them having no forgiveness, but rather he was encouraging them to repent and to obey the Law of Moses more consistently by not showing favoritism. It is contradictory to love God and our neighbor instead of obeying God's instructions for how to do that.