"Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven. " (Matthew 5:19)


Let's take that verse in context:

Matthew 5:17-19
17 “Do not think that I came to destroy the Law or the Prophets. I did not come to destroy but to fulfill. 18 For assuredly, I say to you, till heaven and earth pass away, one jot or one tittle will by no means pass from the law till all is fulfilled. 19 Whoever therefore breaks one of the least of these commandments, and teaches men so, shall be called least in the kingdom of heaven; but whoever does and teaches them, he shall be called great in the kingdom of heaven.

What Christ is saying is that He came to fulfill the law. Man cannot fulfill the law, so Christ fulfilled it for us. Christ goes on to say that heaven and earth will not pass away and not the smallest letter or stroke shall pass away from the Law until all is accomplished. All prophecies in the word of God will be fulfilled at the end of the Kingdom. Then The Great White Throne Judgment will take place, all unbelievers will be cast into the lake of fire forever, and God will create a new heaven and a new earth for all believers for eternity. (Rev 20:11-21:1)

Now for the verse you quoted.

"Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven. " (Matthew 5:19)

What Jesus is referring to is false teachers like the Pharisees who taught the law, but did not follow the law and changed the law to suit their own purpose. They did not believe the scriptures or they would have recognized that Jesus was the Messiah. They were not believers so they would be least in the kingdom of heaven (in other words they would not enter in), but whosoever shall do(believe) the word of God and teach others to believe the word of God, they shall be called the greatest in the kingdom of heaven and will enter in. There are over 600 laws and we cannot even keep the 10 commandments. Some, like the Pharisees, put on a show like they can keep the law, but inwardly they do not believe. Jesus said,

Matthew 23:27
“Woe to you, scribes and Pharisees, hypocrites! For you are like whitewashed tombs which indeed appear beautiful outwardly, but inside are full of dead men’s bones and all uncleanness.

Jesus knows we cannot keep the Law. Jesus kept the Law and fulfilled it for us. Jesus wants us to believe Him, His word and what He has done for us.