Because the NT does not affirm the Sabbath Law as it did the moral commands in the Ten Commandments, one needs to discern the correct doctrine for Christians by considering the following Scriptures.
The NT speaks against sin, sin is the the transgression of God's law, and God's law commands to keep the Sabbath holy. Jesus taught to keep the Sabbath holy both through his interactions with the Pharisees on the topic and by example. In 1 Peter 1:16, we are instructed to be holy for God is holy, which is a quote from Leviticus where God was giving instructions for how to do that, which straightforwardly includes keeping God's Sabbaths holy (Leviticus 19:2-3). In Acts 15:21, the expectation was that Gentiles would hearing Moses taught every Sabbath in the synagogues.
If Jesus thought keeping the Sabbath was an important law, he would have affirmed it on these two occasions, but he did not specifically nullify it either, which jibes/harmonizes perfectly with Paul.
It has always been lawful to do good on the Sabbath, so the issue was not about keeping the Sabbath or not, but about priority. While God commanded His children to rest on the Sabbath he also commanded priests to rest on the Sabbath, however, it was not the case that priests were forced to sin by disobeying one of the two commands no matter what they chose to do but that the lesser command was never intended to be understood as preventing the greater command from being obeyed. This is why Jesus said in Matthew 12:5-7 that priests who did their duties on the Sabbath were held innocent, which David and his men were innocent, and why he defended his disciples as being innocent.
Some Pharisees had reasoned that it is unlawful to work on the Sabbath and that healing is work, therefore it is unlawful to heal on the Sabbath. However, we are also instructed to love our neighbor as ourselves, it would not be loving our neighbor to refuse to heal them, and no command was intended to be understood as preventing us from obeying the greatest two commandments, which is why it was lawful for Jesus to heal on the Sabbath.
Likewise, there is the issue of being permitted to bear false witness in order preserve someone's life, which does not mean that the command against bearing false witness is not important.
9. Paul taught that a person may rest on the Sabbath or not in CL 2:16,
That verse leaves room for two scenarios:
1.) The Colossians were not keeping God's feasts, they were being judged by Jews because they were not, and Paul was encouraging them not to let anyone judge them for not keeping them.
2.) The Colossians were keeping God's feasts, they were being judged by pagans because they were keeping them, and Paul was encouraging them not to let anyone judge them for keeping them.
In Colossians 2:16-23, Paul described the people who were judging the Colossians was promoting human teachings and precepts, self-made religion, asceticism, and severity to the body, which means that they were being judged by pagans that that the second scenario is the case. Those promoting asceticism and severity to the body would be judging people for celebrating feasts, not for refraining from doing that.
In Galatians 4:8-11, Paul addressed those verses to those who formerly did not know God who were enslaved to those that by nature are not gods, which again is describing former pagans. As such, they were not formerly following God's law for how to know Him and Paul could not have been criticizing them for returning to obeying it, so the days that they were returning to was within the context of paganism. In Exodus 33:13, Moses wanted God to be gracious to him by teaching him to walk in His way that he and Israel might know Him, so those who formerly did not know God again does not refer to those who were formerly obeying God's law.
In Romans 14:1, the topic of the chapter is in regard to how to handle disputable matters of opinion in which God has given no command, not in regard to whether followers of God should follow God, so nothing in the chapter should be interpreted as speaking against following God. For example, in Romans 14:2-3, they were judging and resenting each other based on whether or not someone chose to eat only vegetables even though God gave no command to do that.
In Romans 14:4-6, Paul spoke about those who ate or refrained from eating unto the Lord, so he was speaking about those who esteemed certain days for fasting as a disputable matter of opinion. For example, it had become a common practice in the 1st century for people to fast twice a week and people were judging and resenting each other based on whether or not someone chose to do that even though God gave no command to do that (Luke 18:12). Paul was not suggesting that we are free to rebel against God's commands just as long as we are convinced in our own minds that it is ok to do, but rather that was only said in regard to disputable matters of opinion in which God has given no command.
The reason why we are to keep the Sabbath holy is not because man esteemed it as a disputable matter of opinion, but because God rested on it, blessed it, made it holy, He makes us holy, and because God commanded His children to keep it holy. The Sabbath is holy to God regardless of whether or not we keep it holy and what is holy to God should not be profaned by. man, so we would still be obligated to keep the Sabbath holy even if God had never commanded anyone to do that.
10. HB 3:7-4:11 encourages Christians to enter God’s Sabbath rest or salvation by persevering faith in Christ.
In Hebrews 3:18, they did not enter into God's rest because of their disobedience, and in Ezekiel 20:13, it specifically mentions that they greatly profaned God's Sabbaths. In Hebrews 4:9-11, there remains a Sabbath rest for the people of God, we should rest form our work as God rested from His, and we should strive to enter into that rest so that no one may fall away by the same sort of disobedience, so trying to use entering into God's rest in to to justify the same sort of disobedience it the opposite of what is being said.. We should not think that we can have the same sort of disobedience that prevented the Israelites from entering into God's rest and that it will go differently for us.