God has commanded “all men every where to repent: Because He hath appointed a day, in the which He will judge the world in righteousness by that man whom He hath ordained; whereof He hath given assurance unto all men, in that He hath raised Him from the dead”
(Acts 17:30-31)

The reality and substance of true repentance lies in truth of righteousness as in how a sinner is made right with God. Therefore, all righteousness before God must be measured by the glorious Person of Jesus Christ as both God and man (“that MAN whom He hath ordained”) without sin, and in the perfect work He alone accomplished in the redemption of His people when He died on the cross (“in that He hath raised Him from the dead”). Jesus Christ was raised from the dead because of the justification of His people based on His righteousness imputed, and this righteousness was accomplished by His death on the cross. He “was delivered for our offences, and was raised again for our justification” (Romans 4:25). Many claim that to be saved we must repent of our sins. It is better to say that in salvation which is of the LORD, we will repent of our sins. But what does this repentance involve? It is not simply feeling sorry and ashamed for our evil thoughts and acts of immorality, though this is most certainly a necessary part of repentance. But true repentance comes in the power of the Holy Spirit when He convicts us of the fact that we have no righteousness to recommend us unto God. All we think, say, and do (even at our best) falls short of the standard of perfect righteousness which can only be found in the Lord Jesus Christ. The apostle Paul expressed this when he wrote, “But what things were gain to me, those I counted loss for Christ. Yea doubtless, and I count all things but loss for the excellency of the knowledge of Christ Jesus my Lord: for whom I have suffered the loss of all things, and do count them but dung, that I may win Christ, And be found in Him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith.” (Philippians 3:7-9)