The new covenant described in the New Testament is already predicted in the old Testament, see Jeremiah 31:33 and 34.
“For this is the covenant that I will make with the house of Israel after those days, declares the LORD: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people. And no longer shall each one teach his neighbor and each his brother, saying, ‘Know the LORD,’ for they shall all know me, from the least of them to the greatest, declares the LORD. For I will forgive their iniquity, and I will remember their sin no more.”
We see this fulfilled when the Holy Spirit descends on the followers of Jesus on the day of pentacost. ‘God the Spirit’ now lives in us, so that we can really be free of sin and know the Lord.
Reply by Elias
You have shown that in Jeremiah 31:33-34, GOD the LORD of host has promised a new covenant. GOD did try to establish numerous covenant with Israel, his chosen people, but Israel’s sin prevented these promises from being fulfilled. Some of the covenant was delayed, while others did not happen, as Israel did not fulfill their part of the agreement to establish that covenant.
Jeremiah’s ministry was around 626bc to 586bc, near the destruction of the temple of Jerusalem and subsequent 70 years exile of Israel to Babylon.
35 Thus says the LORD, who gives the sun for light by day and the fixed order of the moon and the stars for light by night, who stirs up the sea so that its waves roar– the LORD of hosts is his name: 36 “If this fixed order departs from before me, declares the LORD, then shall the offspring of Israel cease from being a nation before me forever.”
Israel was conquered, temple in Jerusalem was destroyed around 587bc and again in 70AD. Israel depart from GOD’s command and cease to be a nation after Jeremiah’s prophecy. The New Covenant is not established due to Israels’ continual defiance.