The beginning of the story

Many people like the history of the First Covenant. People like to read about Moses. The history of the First Covenant occurred in the mountain. Moses heard from God and Moses wrote the words of God. The author of the First Covenant is God. God gives instruction to his people.  
The First Covenant is great but the law condemns mankind because no person can live without sin. If a person sinned in the First Covenant then the person need an animal sacrifice. The animal sacrifice of the First Covenant explains the cross of Jesus.
Mankind needs forgiveness. A innocent being needs to die for our sins. Jesus lived a perfect life since He is God. He died for the sins of mankind. The cross of Jesus can clean a person soul. Mankind's soul have sin but we can be clean in Jesus. Jesus is the fulfillment of the First Covenant.

Exodus 24:12

 ¹² The Lord said to Moses, “Come up to me on the mountain and stay here, and I will give you the tablets of stone with the law and commandments I have written for their instruction.”