Paul is in favor of the law if it's used correct. This is the same man who said that the Law was not of faith (Galatians 3:12), the Law killed and condemned (Corinthians 3:7), the Law strengthened sin (1 Corinthians 15:56), and the Law made sin come alive in us (Romans 7:11). Here, Paul was saying that there is a good use of the Law.
In regard to 2 Corinthians 3:7, Deuteronomy 30:15-20 is up front that God's Law is a ministry of life and blessing if we are obedient and a ministry of death and cursing if we are not, so that fact that the law brings death for disobedience is hardly a good reason to live in disobedience to it.
In Romans 7:21-25, Paul said that he delighted in obeying God's Law and that he served it with his mind, but contrasted that with a law of sin that held him captive and that he served with his flesh. This is a summary of what was said before, it is the law of sin that came about to increase tresspasses (5:20), that held him captive (7:5), that stirred up sinful passions to bear fruit unto death (7:6), that gave sin its power (7:8), that caused sin to come alive (7:9), that seized the opportunity through the commandment to deceive and kill him (7:11), and that caused him not to do the good that he wanted (7:13-20), However, it is God's Law that was given to reveal what sin is (7:7), that is holy righteous, and good (7:12), that is the good that paul did not blame (7:13), and that is the good that he sought to do (7:13-20). So Romans 6:14 and 1 Corinthians 15:56 are likewise referring to the law of sin.
Paul was never against the Law of God; he was just against it as a means of obtaining right relationship with God (Romans 3:31).
The way to obtain a right relationship with God is through faith and by the same faith we are to uphold the law by living in obedience to it.
This was not its purpose (Romans 3:19). The Law is good if it is used to condemn people and bring them to a place where there is no deception about self-salvation. If the Law is used in that way, then it is good.
The Law is holy, righteous, and good straightforwardly because it is God's instructions for how to do what is holy, righteous, and good (Romans 7:12-13), which we are still told to follow as part of the New Covenant (1 Peter 1:13-16, 1 John 3:10, Ephesians 2:10).
The problem comes when people who have already come to the Lord for salvation try to continue to improve upon that relationship by their works, or by keeping of the Law. This is not right. The Law isn’t for those who are righteous through Jesus (1 Timothy 1:9).
That is to help explain 1 Tim 1:8
Speed limits are not for people who would normally drive at safe speeds even if there were no speed limits, but rather they are needed for people who would otherwise drive at unsafe speeds. In the same way, the Law is not needed for a righteous person because they are already doing what the Law requires, but rather the Law is needed to correct those who are not doing what is righteous. So if someone thinks that obeying the Law is not for them, then they are showing themselves to be precisely someone whom the Law is for.
It is indeed a problem if someone were to try to improve upon their relationship with God by keeping the Law, but it is important to understand that the Law was never given for that purpose in the first place, so it is a problem because it is a legalistic perversion of the Law. The one and only way to grow in a relationship with God is through faith and by the same faith we are required to live in obedience to God's Law, so obedience to the Law is an outworking of our faith in God to guide us in how to rightly live, not something ever intended to be done apart from faith.
My personal belief would be that it would be sin to punish people accord to the law of Moses today (Those punishments were harsh and extreme, but they served their purpose of teaching people that sin was wrong). The old covenant came with the rules and regulation, but we are now under a new covenant and so I believe we have been freed from those types of punished/curses. Yes, there are still consequences to sin, and that's why God established the worldly authorities in order to bring about justice and what not. And yes, it was wrong what the Catholics did during those times. I hope that helped answer your question.
God's Laws are His instructions for how to act according to His attributes, so His holiness, righteousness, goodness (Romans 7:12), justice, mercy, faithfulness (Matthew 23:23), and other fruits of the Spirit (Exodus 34:6-7). For example, Leviticus 11:44-45 and 1 Peter 1:13-16 say to have a holy conduct because God is holy, so following those instructions is about acting according to the holiness of our God. If taking a particular action was in accordance with God's righteousness before Christ came, but now is no longer in accordance with God's righteousness, or vice versa, then God's righteousness has changed, but God's righteousness is eternal and unchanging (Psalms 119:142) and so therefore are all of His righteous laws (Psalms 119:160). So while we are indeed under a New Covenant with better promises and superior mediator, we do not have superior laws because that would involve following a superior God with superior attributes.
