1 - Jesus did not commanded to preach the Old Testament laws. Jesus Christ commanded preach only the Gospel to all people:
"Go into all the world and preach the gospel to the whole creation. He who believes and is baptized will be saved; but he who does not believe will be condemned". (Mark 16:15-16)
2 - The True Law of God is from always to everlasting, not expired. The laws expired are the Old Testament laws that Jesus Christ abolished (Matthew 5:31-48 and the entire context of the Gospel).
3 - The first five books are called "law of Moses", but the true Law that God gave to Moses is the Law that Jesus taught us in the Gospel, because Jesus tells us this is the Law and the Prophets:
"all things whatsoever ye would that men should do to you, do ye even so to them: for this is the law and the prophets". (Matthew 7:12)
4 - Many of the 613 commandments of the Old Testament were abolished by Jesus Christ, and Christians are not under those orders of the Old Testament, because many of them were only precepts of men.
True Law of God taught by Jesus Christ tells us so:
"Therefore all things whatsoever ye would that men should do to you, do ye even so to them: for this is the law and the prophets" (Matthew 7: 12)
Jesus teaches to a rich man, the precepts of the Law
"And behold, one came to him and said, Teacher, what good thing shall I do, that I may have eternal life? And he said unto him, Why askest thou me concerning that which is good? One there is who is good: but if thou wouldest enter into life, keep the commandments. He saith unto him, Which? And Jesus said, Thou shalt not kill, Thou shalt not commit adultery, Thou shalt not steal, Thou shalt not bear false witness, Honor thy father and mother; and, Thou shalt love thy neighbor as thyself. The young man saith unto him, All these things have I observed: what lack I yet? Jesus said unto him, If thou wouldest be perfect, go, sell that which thou hast, and give to the poor, and thou shalt have treasure in heaven: and come, follow me. But when the young man heard the saying, he went away sorrowful; for he was one that had great possessions" (Matthew 19: 16-22
These are the commandments of the Gospel, which are very different to the commandments of the Old Testament, for all the commandments of the Gospel are merciful, but many Old Testament commandments commands death sentences, wars and slavery.