What part of the Law of Moses are we under?

This question must first be answered with a question: What do you mean by “under?” In Hebrews 8, the writer contrasts the covenant God made with Moses to the covenant in Christ. With the Law of Moses in view (Heb 3:4), the author calls it old and fading (Heb 8:13)! In Galatians, we see Paul chiding the Galatians for attempting to be justified before God based on works of the law. Contextually, “law” should be understood as Mosaic Law (Gal 3:7). At this point, some may become uneasy and protest, “God calls us to be holy!” True, God does call us to be righteous, but not according to how we would imagine. Paul, in fact, declares that the Law has no life (Galatians 3:21)! At the end of the day, the real issue with the law is that our sinful nature prevents us from fulfilling it (Romans 8:3).

Why the law, then? According to Galatians 3:19, law was given because of transgressions. In other words, the Law was given to curb sin. In fact, Paul goes on to say that the Law holds us captive (vs 23). This Law, though holy (Rom 7:12), is merely a tutor to lead us to Christ (Gal 3:24). The Law, because of our sinful nature, is useful for demonstrating how we are unable to live holy, but it is useless for actually bringing freedom and life. The freedom and life is found through faith in Christ (Gal 3:23-26).

Now, when dealing with this subject more thoroughly in Romans, Paul also warns us not to conclude that sinning is perfectly fine. The fact is, if we are set free from sin, we certainly do not want to return to it, for it only brings death (Romans 3:23). So, our Justification is firmly rooted in faith in Christ. In other words, we are not under the Law of Moses.

In terms of our Sanctification, I believe we have to talk to the Holy Spirit with how to deal with the Law of Moses. After all, faith in Christ fulfills the Law of Moses (Rom 10:4), so we are not obligated to it. Jesus himself declared all food clean (Mark 7:18-19) and the apostolic witness is clear that believers are not bound to festivals, Sabbaths, etc. (Col 3:16). It would be an error to think our righteousness, even just a little, is contingent upon obedience, but it is also error to think that adultery or lying are now acceptable or beneficial. Since the Law is only a shadow of the good things to come (Col 2:7, Heb 10:1) we must ask what is actually behind the Mosaic Law. Jesus clarified this in a number of places (Mark 2:27, Matt 22:38-39). However, it still must be maintained that our righteous standing before God is not dependent on our Sanctification, but that Sanctification is an outworking of Justification.