The Bible commands repentance (Acts 2:38; 3:19), and also tells us it is a gift from God (2 Timothy 2:25). We can repent because God's grace enables it. We marvel at Christ's life and death, and we turn toward Him for hope, healing, and forgiveness. Glory to God, we must and can turn from sin,
Likewise, the Bible warns there are false versions of repentance; the best passage on this comes from: 2 Corinthians 7:10-11 (NIV):
Godly sorrow brings repentance that leads to salvation and leaves no regret, but worldly sorrow brings death. See what this godly sorrow has produced in you: what earnestness, what eagerness to clear yourselves, what indignation, what alarm, what longing, what concern, what readiness to see justice done. At every point you have proved yourselves to be innocent in this matter.
Worldly sorrow is flash-in-the-pan guilt. It's tears, frustration, and disappointment about sin and its consequences in our lives. But, it's world focused rather than God focused. The repentance that saves and sanctifies is first and foremost a reorientation toward God.
At the heart level, we come to hate the sin, guilt, and shame we've incurred by acting or thinking in a morally evil way before a holy God. We see God's love, foremost on the Cross of calvary, and seek to honor Him who saved us. We know our repentance doesn't save us, but we also know saved people must repent (similar to James' concern with faith and works in James 2).
At the level of the will, by the Holy Spirit, we crucify the passion and unbelief that led us to sin against God (Rom 8:13; Colossians 3:5). We won't go that way again because we smell the death, destruction, and horror of such a path. We work out our salvation with fear and trembling because the Spirit is at work in us to obey God's holy will (Philippians 2:12-13).
Note the various behaviors/attitudes associated with true godly sorrow and repentance from 2 Corinthians 7:11 -
1. Earnestness: This means we become diligent and careful to avoid any of the temptations that led up to our sin before God. We guard our minds, our hearts, and our bodies. We're earnest to honor God. We don't ask, "Is this sinful or not?" We ask, "What does holiness and pleasing God look like?" Elsewhere we read in Scripture that we should not allow anyone to look at our lives and quickly suspect us as greedy, sexually immoral, or impure (not even a hint, Ephesians 5:3). And why, Paul goes on and says, "For of this you can be sure: No immoral, impure or greedy person-- such a person is an idolater-- has any inheritance in the kingdom of Christ and of God." (Ephesians 5:5, NIV) Are you earnest to turn away from sin in order that you might inherit the kingdom of God?
2. Eagerness to clear ourselves: This does not mean we make excuses for our past behavior, but rather we endeavor to live such profound lives of marked change that no one would doubt our repentance. This is a tricky one because we all know how to make people believe we've repented. So, this starts at our heart. God hates hypocrisy. We must fall on our knees and beg God to forgive us, change us, transform us, renew us. Oh, that our hearts would hold onto God until He grants us a total, complete repentance that is authentic, vibrant, and evident to all.
3. Indignation: This is a holy hatred of sin and a willingness to confess, as Paul, that I am the chief of sinners (1 Timothy 1:15-16). The terror of hell still grips me, the condemnation of sin lingers in my memory, and the unlikely escape from eternal punishment is not forgotten. Connect this with God's redeeming love, and what flows from the heart is a holy indignation toward sin and its effects.
4. Alarm: This is sobered fear. This is firmly believing the truth of Hebrews 10:26-27 "If we deliberately keep on sinning after we have received the knowledge of the truth, no sacrifice for sins is left, but only a fearful expectation of judgment and of raging fire that will consume the enemies of God." Especially for the Christian, any ongoing sin should produce in us sobered fear. Let this fear send you back to God's love in Christ and the mercy that comes from Jesus' death.
5. Longing: Every sin disrupts our relationship with God. It's a vital break in our fellowship. Biblical repentance involves a desperate longing for the unhindered reconnection that is possible through the blood of Jesus. We come running because of the promises in 1 John 1:7 & 9:
NIV 1 John 1:7 But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus, his Son, purifies us from all sin.
NIV 1 John 1:9 If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness.
6: Concern: Next up is a refreshed zeal for the LORD God. We're jealous for Him. We're concerned to keep Him the priority of our lives. We want nothing to come in between. We want nothing to separate us from the love of God that is in Christ Jesus...and praise God, nothing ultimately can (Romans 8:29ff.).
7: Readiness to see justice done: This is a firm commitment to avenge all wrong doing. If we sinned against a spouse or friend, we make things right (with time, money, service, earning back trust, public confession, etc.). If we sinned against our local church, we accept their counsel for making things right and for walking in open fellowship. Repentance of the heart is never calculating. We don't say, "There, I repented by doing X, Y, and Z, all should be well." Biblical repentance knows that ultimately Christ's death is our only hope, atonement, and true freedom. We rest in Christ's satisfaction for sin. We never, ever, turn to penance to atone for our temporal punishments. And yet, Paul says, we give the rest of lives to outdoing one another in love, continuing with a moral obligation to love one another. Biblical repentance includes a commitment to justice, restitution, and ultimately for making sure God's name is honored.
We must never short circuit repentance into easy-believism or 'forgive and forget' nonsense. This is a blood-bought privilege from Jesus Christ that will be clearly seen, and when it occurs, everyone will know it's a work of God and praise Him (not you or me). Everyone knew Zacchaeus had repented (Luke 19). Paul's conversion and repentance was known by all (Acts 9ff.). The sexual immoral man from Corinth demonstrated full repentance (see 1 Cor. 5 and 2 Cor 7).
May God grant you and me repentance today, whether it's repentance to salvation or a repentance unto sanctification. And may our repentance receive the commendation in 2 Cor 7:11: At every point you have proved yourselves to be innocent in this matter.
You might appreciate another accounting of Biblical repentance at http://cornerstonecf.net/2013/08/12/the-nature-of-true-repentance-thomas-watsons-six-ingredients/