God gave the promise of a new covenant because the people of Israel had failed Him. He also did so because the Old Mosaic Covenant did not have the power to enable them to remain faithful to God. The New Covenant has the power whereby God"s people may remain faithful, namely, the presence of God living within the believer (i.e, the Holy Spirit). This is one way in which it differs from the Old Covenant ( Hebrews 8:9). [1][source]
God promised that the New Covenant would enable the Israelites to do four things. They would know and desire to do God"s will ( Hebrews 8:10 b), enjoy a privileged, unique relationship with God ( Hebrews 8:10 c), know God directly ( Hebrews 8:11), and experience permanent forgiveness of their sins ( Hebrews 8:12). These are the "better [2] promises" the writer referred to earlier ( Hebrews 8:6). [source][source][source]
". . . new covenant promises are not yet fully realized. The promises in Jeremiah ,, Isaiah , and Ezekiel describe a people who have the law written in their hearts, who walk in the way of the Lord, fully under the control of the Holy Spirit. These same promises look to a people who are raised from the dead [3], enjoying the blessings of an eternal inheritance with God dwelling with them and in them forever." [4][source]