Ezekiel 11:19 English Standard Version (ESV) And I will give them one heart, and a new spirit I will put within them. I will remove the heart of stone from their flesh and give them a heart of flesh,

This is how the New Testament differs from the demands of Deuteronomy 6:25

Colossians 3:14-16 English Standard Version (ESV)

¹⁴ And above all these put on love, which binds everything together in perfect harmony. ¹⁵ And let the peace of Christ rule in your hearts, to which indeed you were called in one body. And be thankful. ¹⁶ Let the word of Christ dwell in you richly, teaching and admonishing one another in all wisdom, singing psalms and hymns and spiritual songs, with thankfulness in your hearts to God.

Philippians 3:9 English Standard Version (ESV) and be found in him, not having a righteousness of my own that comes from the law, but that which comes through faith in Christ, the righteousness from God that depends on faith—

To know right and to do right is impossible without our faith in Christ, who is our one heart, who dwells in all who have accepted Him by faith. This walk of faith is in the spirit yet we live in the flesh. We are subject to all the ills of the flesh. All of our sufferings are in the flesh. We have the ability to obey the flesh or the spirit. Love will always be a choice.

Romans 7:18 English Standard Version (ESV) For I know that nothing good dwells in me, that is, in my flesh. For I have the desire to do what is right, but not the ability to carry it out.

Paul tries in Romans 7 to explain how difficult it is to live in these two worlds, the flesh and the spirit. Trying to find the strength in the flesh to carry out the will of God is impossible.

Romans 7:24-25a English Standard Version (ESV)

²⁴ Wretched man that I am! Who will deliver me from this body of death? ²⁵ Thanks be to God through Jesus Christ our Lord!

Deuteronomy 6:25 English Standard Version (ESV) And it will be righteousness for us, if we are careful to do all this commandment before the Lord our God, as he has commanded us.’

This will be our righteousness, if we do the commands. This is the Old Testament standard requirement for righteousness. Here is the command.

Deuteronomy 6:4-9 English Standard Version (ESV)

⁴ “Hear, O Israel: The Lord our God, the Lord is one. ⁵ You shall love the Lord your God with all your heart and with all your soul and with all your might. ⁶ And these words that I command you today shall be on your heart. ⁷ You shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise. ⁸ You shall bind them as a sign on your hand, and they shall be as frontlets between your eyes. ⁹ You shall write them on the doorposts of your house and on your gates.

Try as they might, they failed and they had no righteousness of their own.

Romans 3:9-11 English Standard Version (ESV)

No One Is Righteous

⁹ What then? Are we Jewsany better off? No, not at all. For we have already charged that all, both Jews and Greeks, are under sin, ¹⁰ as it is written: ¹¹ “None is righteous, no, not one; no one understands; no one seeks for God.”

The failings of the followers was in their ability to love with all heart, all soul and all strength. There was no inner strength within them capable of giving all. Self-interest remained an issue because the heart had not changed.

Ezekiel 11:19 English Standard Version (ESV) And I will give them one heart, and a new spirit I will put within them. I will remove the heart of stone from their flesh and give them a heart of flesh,

Ezekiel 36:26 English Standard Version (ESV) And I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh.

It was so important that Ezekiel repeated it twice with one exception, this new heart was one heart.