The Bible is divided into the Old Testament and the New Testament. The Old Testament refers to the Ten Commandments received at Mount Sinai. And the new covenant refers to the Holy Spirit that came upon the body of the saints. Just as the building containing the Ten Commandments became a temple, the body of the saint who received the Holy Spirit becomes a temple in heaven. The fact that the new covenant is the Holy Spirit can also be confirmed through the actions of Moses. B.C. Around 1500, God sent nine plagues on the land of Egypt through Moses. He brought plagues on Egypt to liberate Israel. But Pharaoh, king of Egypt, did not let Israel go. Because of this, God sent a calamity that killed all the firstborn, and Israel had to keep the Passover sacrifice on January 14th in the Jewish calendar to avoid disaster. Israel, liberated by this incident, left Egypt at dawn on January 15 and arrived in front of the Red Sea on January 21. They crossed the Red Sea and reached Mount Sinai in 40 days. And ten days later, Moses went up the mountain to receive the Ten Commandments. 

Following in the footsteps of Moses, Yehoshua fulfilled the prophecy: He died on the cross at 3 p.m. on January 14, the day the Passover lamb was sacrificed in Egypt. Just as Israel, freed from Egypt with Moses, suffered as they were chased by Egyptian soldiers until they crossed the Red Sea, so the disciples suffered as Yehoshua lay in his grave. Just as the Israelites crossed the Red Sea and reached Mount Sinai in 40 days, Yehoshua was taken up into heaven on the 40th day after his resurrection, and ten days later the Holy Spirit was poured out on the day of Pentecost. This was the 50th day after Moses crossed the Red Sea and the day he went up to Mount Sinai and received the Ten Commandments. God set aside this day as Pentecost. 

Therefore, a careful study of the works of Moses will reveal what the new covenant is that Joshua establishes. Paul testified in Galatians that the Old Covenant was the Ten Commandments received at Mount Sinai, so what is the New Covenant? According to Moses' actions, the New Covenant, like the Old Covenant, must be established on the Day of Pentecost, when Moses went up to Mount Sinai and received the Ten Commandments. According to Moses' deeds and prophecy, the New Covenant is the Holy Spirit who descended at Pentecost. 

Through the temple system, we can confirm what the new covenant is. Moses built the temple to contain the Old Covenant, the Ten Commandments. So there is a covenant in the temple. So, who is the New Testament temple? In the New Testament era, the temple is the saints who have received the Holy Spirit. 

[1 Corinthians 3:16] All of you surely know that you are God's temple and that his Spirit lives in you. Together you are God's holy temple, and God will destroy anyone who destroys his temple. 

In the temple is the covenant of God. The temple established on earth through Moses had the Ten Commandments, so the Old Testament law refers to the Ten Commandments. The New Testament temple is the saints, and the Holy Spirit who dwells in them is the substance of the New Covenant. Therefore, the New Covenant refers to the Holy Spirit. Physical Israel received the Ten Commandments on Mount Sinai, but spiritual Israel receives the New Covenant on Mount Zion in heaven. So who will receive the Holy Spirit? 

[Isaiah 59:20~21] The Redeemer will come to Zion, to those in Jacob who repent of their sins," declares the LORD. "As for me, this is my covenant with them," says the LORD. "My Spirit, who is on you, and my words that I have put in your mouth will not depart from your mouth, or from the mouths of your children, or from the mouths of their descendants from this time on and forever," says the LORD 

The evidence of Scripture is that the Holy Spirit, which comes down from heaven, is given to those who repent. Those who repent will receive the Spirit of God and the Word of God. This is the promise God made to his people. Therefore, the New Covenant is a promise to give the Holy Spirit.