According to New Testament teaching, we, as Christians, are not required to keep the Law of Moses. Period. This is confirmed by Matthew 5:17-18 in which we learn that Jesus fulfilled the Law (of Moses). Paul tells us multiple times that we, as Christians, are not required to uphold the Law of Moses. This is found in Colossians 2:13-15, Colossians 2:16-19, Galatians 5:1-4 and many others. In fact, Paul makes it clear in Galatians that, if we bind the Law of Moses on Christian believers, we have denied Christ!
Some believers have tried to get around this by defining different kinds of Mosaic laws. For example they have talked about the “ceremonial law”, the “judicial law” and the “moral law.” The problem with this is that these distinctions are never made in the Old Testament. Such believers have said we are not under most of the Laws of Moses but we are under the Ten Commandments, which are part of the “moral law.” Again, this is not supported by the New Testament. My conclusion is that we are not required to obey the laws given to Moses. End of story. Or put it a slightly different way. If we are required to observe any of the laws in the Ten Commandments, we are required to do so, not because they are in the Law of Moses, but for other biblical reasons.
This does not mean that it is OK to covet our neighbor’s wife or to take the Lord’s name in vain, or to murder. We have plenty of passages in the New Testament which inform us that murder is sinful, as are lying, coveting our neighbor’s wife and jealousy. In fact, nine of the ten commandments are found, in one form or another in the New Testament. Therefore, we do not give false testimony because Jesus would have us not give false testimony. Just because we are not subject to the Law of Moses, does not mean that it is OK to give false testimony. So, the Ten Commandments are not binding on us, but many of the things in those Ten Commandments still hold, not because they are part of the Law of Moses, but because Jesus told us those things as well. The only of the Ten Commandments NOT implied in the New Testament is the Sabbath law. We are not bound to Sabbath law. We can observe a Sabbath if we like, but we are not bound to it. The Colossians passage referenced above makes this clear.
Any commandment given to Moses, but also given to us by Jesus applies to us, not because it was in the Law of Moses, but because it was given to us by Jesus, or perhaps one of his apostles.
I hope this makes sense to you.