1 Corinthians 1:30-31
But by His (the Father’s) doing you are in Christ Jesus, who became to us wisdom from God, and righteousness and sanctification, and redemption, that, just as it is written, “Let him who boasts, boast in the Lord”.
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The apostle Paul writing here to the believers in Corinth would certainly have well known from his previous time of life as Saul, a Pharisee, that God Himself had spoken through the prophet Jeremiah to say: “Let not a wise man boast of his wisdom, and let not the mighty man boast of his might, let not a rich man boast of his riches; but let him who boasts boast of this, that he understands and knows Me…” {Jer.9:23-24}
 
Paul called himself the foremost, the 'chief' of sinners, {1Tim.1:15} and yet also speaks of the positive things in his life and ministry as he writes to the Philippians—“although I myself might have confidence even in the flesh. If anyone else has a mind to put confidence in the flesh, I far more: circumcised the eighth day, of the nation of Israel, of the tribe of Benjamin, a Hebrew of Hebrews; as to the Law, a Pharisee; as to zeal, a persecutor of the church; as to the righteousness which is in the Law, found blameless.” {Php.3:4-6} Of course he continued on to say: “But whatever things were gain to me, those things I have counted as loss for the sake of Christ.” {Php.3:7}

He pretty much summarized his theology in this statement: “For I determined to know nothing among you except Jesus Christ, and Him crucified.” {1Cor.2:2) The apostle Paul's sins, like yours and mine, have been washed away in the flow of Jesus' blood, shed on the cross and are now forgotten, pardoned and cast away “as far as the east is from the west”. {Ps.103:12}

While Satan the father of lies still goes about as a roaring lion seeking who he can devour {1Pt.58} the Lord, has promised that the redeemed of the Lord, all of us who have believed and received Him, that no weapon that is formed against you will prosper; And every tongue that accuses you in judgment you will condemn. This is the heritage of the servants of YHWH, the Lord, and their vindication is from Me. {Is.54:17}
 
Thanks be to God, who gives us the victory through our Lord Jesus Christ. {1Cor.15:57} So we must remember above all that our righteousness was absolutely not because we were wise or mighty, and certainly not because of our riches—for the redemption of our souls is costly! {Ps.49:8} Now, rejoice....

“For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, that no one should boast.” (Ephesians 2:8-9)
 
REJOICE IN THE LORD ALWAYS