In the beginning of the second chapter, Paul talks about the council of Jerusalem and the debate about the necessity of circumcision. Most of the apostles were taken up by the false teaching, but Paul was able to challenge this direction. Through the centuries, the Church always goes through turbulence as to the teachings of Jesus Christ. We humans, in our ignorance and some in their malice, try to promote new false teachings about Jesus and morals. These false teachings are very important to correct.
What a person believes, they act on. If you believe someone is acting out of malice, you respond as if it were true. You may get angry, start judging them, gossip, or even will the evil for them. But if you know the person did not mean it, then you may be more forgiving. What we perceive to be reality, we act on. If we are not sure, we are slow to act on it.
Many Christians think that God loves them for what they do, be it following the law or doing nice things. For some it is a matter of checking the box, so they can think God owes them heaven, or by doing so many good things to outweigh the bad. It is kind of like buying flowers for the wife when you get in trouble. If this is what a person believes, they act accordingly. Some will do many great things, only to burn themselves out or have a chip on their shoulder. Others will live a lukewarm life, checking off the box but never coming to a relationship with God, resenting the checkbox. This mentality steals faith away and sets them up for hell. This is why Paul is so passionate about this subject.
The New Law is to be placed in our hearts when we respond to God’s gift. The New Law is the fulfillment of the Old Law. The standard of the New Law is actually harder to follow. The Old Law dealt with the checklist of physical and observable actions, whereas the New Law pierces into the heart, because it gets into the motives with the interior life. This makes sense. Jesus died on the cross for you, not so you would have a superficial relationship with Him. He wants a deep relationship with you. If this is reality, then you would act accordingly.
We are judged by our relationship with God. When we judge relationships with others, we look at how they treated us (morals), their interactions with us and our loved ones (worship), the conversations we have (prayers), the trust we have in each other (faith) and more. This does not mean the Old Law is no good (v17-18). God is still offended by transgressions against the Ten Commandments; anybody who says otherwise is not with God.
It is the laws of Moses that were changed, or rather, transformed to heighten our relationship with God. Circumcision was a means by which the Jewish people were claimed by God the Father as a prefigurement of baptism. The manna in the desert was a symbol of the Eucharist we have at Mass. Moses is a symbol of Jesus, but also the pope and the priesthood interceding for the people. The mere symbols give way to the sacraments and the reality they convey. The reality they convey is God’s grace: mercy, peace, joy, purity, love and healing. So the sacraments do not convey law; they convey the heart of God for each soul according to the needs of each soul.
That is how God would enter into a relationship with us.