God says THOSE WHO OBEY BY REPENTING of their SINS get a new heart!
Ezekiel 18:31 Rid yourselves of all the offenses you have committed, and get a new heart and a new spirit. Why will you die, people of Israel?
The natural man is about a man who ONLY lives to please his flesh.
NOT everyone only lives to please their flesh.
We are not just flesh people, we are also spirit.
Some people want more out of this life than merely pleasing their flesh.
Paul is quoting Psalm 14:1-3; 53:1-3; and Ecclesiastes 7:20. Ecclesiastes SAYS there is not a RIGHTEOUS man who does what is right and NEVER SINS. Ecclesiastes tells us that there ARE RIGHTEOUS men but none who NEVER sin. Paul is explaining that the Jews were sinners just like the Gentiles. Nowhere in these passages or scriptures anywhere does it say none can believe on their own. In this same Ecclesiastes 7, Solomon tells us about wise men, righteous men, and about a man who pleases God. Solomon also tells us that he found one upright man among a thousand. The Bible tells us that there are people who want to do right.
I explained this to you before. In Ezek. 18:31 God is speaking to His Covenant People Israel, the same ones Christ was their Covenant Head and Surety Heb. 7:22 in the Everlasting Covenant of Grace, as David speaks of here:
2 Sam. 23:5
Although my house be not so with God; yet he hath made with me an everlasting covenant, ordered in all things, and sure: for this is all my salvation, and all my desire, although he make it not to grow.
The same People God promised to give a New Heart and New Spirit Ezek. 36:26-27, and Repentance.
Acts 5:31
Him hath God exalted with his right hand to be a Prince and a Saviour, for to give repentance to Israel, and forgiveness of sins.
Acts 11:18
When they heard these things, they held their peace, and glorified God, saying, Then hath God also to the Gentiles granted repentance unto life.
So you see, God-given Faith Phil. 1:29, Repentance results in a conversion experience for all those Christ shed His Blood for in the Everlasting Covenant of Grace.
But before a person is converted, Born of the Spirit, they are still in the flesh / carnal and cannot please God Rom. 8:8.
John 3:6-7
6 That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.
7 Marvel not that I said unto thee, Ye must be born again.
And one more thing!
All men sin. But the Blessed ones Christ made Righteous Rom. 5:19; 5:9 by His Blood Rev. 13:8, no sin was ever imputed to them, but to their Surety instead from Everlasting Is. 53:6.
Rom. 4:6-8
6 Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works,
7 Saying, Blessed are they whose iniquities are forgiven, and whose sins are covered.
8 Blessed is the man to whom the Lord will not impute sin.