Why do we use this phrase? Why do we make such a bold claim? Let’s let the Word of God speak for itself
“Behold, the days are coming, says the Lord, when I will make a new covenant with the house of Israel and with the house of Judah— not according to the covenant that I made with their fathers in the day that I took them by the hand to lead them out of the land of Egypt, My covenant which they broke, though I was a husband to them, says the Lord. But this is the covenant that I will make with the house of Israel after those days, says the Lord : I will put My law in their minds, and write it on their hearts; and I will be their God, and they shall be My people. No more shall every man teach his neighbor, and every man his brother, saying, ‘Know the Lord,’ for they all shall know Me, from the least of them to the greatest of them, says the Lord. For I will forgive their iniquity, and their sin I will remember no more.”
For your Maker is your husband, The Lord of hosts is His name; And your Redeemer is the Holy One of Israel; He is called the God of the whole earth. For the Lord has called you Like a woman forsaken and grieved in spirit, Like a youthful wife when you were refused,” Says your God. “For a mere moment I have forsaken you, But with great mercies I will gather you. With a little wrath I hid My face from you for a moment; But with everlasting kindness I will have mercy on you,” Says the Lord, your Redeemer. “For this is like the waters of Noah to Me; For as I have sworn That the waters of Noah would no longer cover the earth, So have I sworn That I would not be angry with you, nor rebuke you. For the mountains shall depart And the hills be removed, But My kindness shall not depart from you, Nor shall My covenant of peace be removed,” Says the Lord, who has mercy on you.
As a result of the once and for all sacrifice of Christ as the sin offering for the world, God would no longer be angry with us.
2 Corinthians 5:17-21
Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new. And all things are of God, who hath reconciled us to himself by Jesus Christ, and hath given to us the ministry of reconciliation; To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them; and hath committed unto us the word of reconciliation. Now then we are ambassadors for Christ, as though God did beseech you by us: we pray you in Christ’s stead, be ye reconciled to God. For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.
This is the fulfillment of Jeremiah and Isaiah's prophecies about the New Covenant and God's everlasting Gospel of PEACE.
Romans 1:16, 17
For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith.