The Old Testament laws were to be valid only up to the coming of John the Baptist
Luke 16 : 16 & 17, Matthew 5 : 17 – 18 , Hebrews 7
The Old Testament Laws that God gave to Moses and to the Levitical priestly system were to be taught and obeyed until the second coming of Elijah, (that is John the Baptist)!
After that, the “Good News” were to be proclaimed to everyone:
All who believed and submitted themselves to Jesus could enter in the Kingdom of God through Faith and Obedience in him who was the promised Messiah and the Eternal High Priest of a New Priestly System!
And since a change of the priestly system implies a change of Laws, (Hebrews 7: 12), Jesus replaced the imperfect “written Law” by a law that summarizes all Laws it contained, if properly led, in all sincerity by the Holy Spirit of God:
“Love God above everything else, and treat your fellow men as you would like to be treated yourself…”
It would have been easier for heaven and earth to disappear rather than bringing a change in the Laws of God as written in the Old Testament, and indeed a far greater and more important event made this transition possible:
Jesus Christ, the Only Son of God, our Eternal High Priest came to earth, suffered and died for mankind’s salvation, and set us free from a set of Laws that were incomplete and were mis-interpreted until then as being a “ticket” to Heaven!