Truth

Premise
Moses’s law has been nullified and Christ’s law has been substituted for instead. However, this substitution has been surprising so many people. What is Christ’s law?
1 Corinthians 9:20-21

“To the Jews I became like a Jew, to win the Jews. To those under the law I became like one under the law (though I myself am not under the law), so as to win those under the law. To those not having the law I became like one not having the law (though I am not from God’s law but am under Christ’s law), so as to win those not having the law.”

So, Apostle Paul was under Christ’s law.

Theme
Why and when did Christ’s law - the new law - appear?
Hebrews 8:7,13

“For if there had been nothing wrong with that first covenant, no place would have been sought for another…. By calling this covenant ‘new’, he has made the first one obsolete; and what is obsolete and aging will soon disappear.”

Since the first covenant, Moses’s law, had been obsolete and incomplete, the second covenant, the new covenant, was announced by Jesus Christ.
Hebrews 7:12

“For when there is a change of the priesthood, there must also be a change of the law.”

Since the priesthood of Moses’s law had not been incomplete, there needed to be another priesthood that would complete Moses’s law. The new law was established by Jesus Christ. And He said:
Matthew 5:17

“Do not think I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them.”

Therefore, we, God’s people, should bear in mind His law.
Isaiah 51 :7

“Hear me, you who know what is right, you people who have my law in your hearts: Do not fear the reproach of men or be terrified by their insults.”

Proverbs 28:9

“If anyone turns a deaf ear to the law, even his prayers are detestable.”

Proverbs 28:4

“Those who forsake the law praise the wicked, but those who keep the law resist them.”

God’s children are willing to resist the wicked, obeying His law.
Revelation 12:17

“Then the dragon was enraged at the woman and went off to make war against the rest of her offspring - those who obey God’s commandments and hold to the testimony of Jesus.”

Revelation 14:12

“This calls for patient endurance on the part of the saints who obey God’s commandments and remain faithful to Jesus.”

1 John 2:3-6

“We know that we have come to know him if we obey his commands. The man who says,’ I know him,’ but does not do what he commands is a liar, and the truth is not in him. But if anyone obeys his word, God’s love is truly made complete in him. This is how we know we are in him: Whoever claims to live in him must walk as Jesus did.”

Matthew 15:7-9

“You hypocrites! Isaiah was right when he prophesied about you:’ These people honor me with their lips, but their hearts are far from me. They worship me in vain; their teachings are but rules taught by them.”

Conclusion
Psalms 119:

“You [God] rebuke the arrogant, who are cursed and who stray from your [God’s] commands.”

Let’s abide by Christ’s law, the New Covenant, so that we may be allowed to enter the kingdom of heaven.