In scripture, repentance means to "undergo a change of one's mind" which results in a change of the entire direction of a person's life.
Biblical repentance is a radical turning away from sin and towards Jesus. It is a key element of saving faith
According to the Bible, repentance and faith go together. There can be no genuine turning to Jesus in faith without an accompanying repudiation of sin.
The Bible explains that in the past you and I were spiritually dead, unfeeling towards God. We followed the ways of this world and, even though we didn't realize it, we obeyed Satan, who rules the world. Satan has power over everyone who is dead to God. Before you and I were born again, we were also ruled by the selfish desires of our human natures. Because of this, we were already under God's wrath.
But look at how Jesus was with this Samaritan woman. That is the picture of God's real mercy! We were dead because of our sins, but God loved us so much that He made you and me who received Him alive with Messiah Jesus. It is God's wonderful kindness which saves you and me, which woos us to repentance, and flows into our lives when we repent.
As a person hears the gospel, understands it, and accepts it, God's regeneration of that person from being dead in their sins to being spiritually alive, and that person's repentance and calling on God all seem to happen together.
True repentance involves three important steps:
1) Conviction: Becoming convinced, through the work of the Holy Spirit, that what you have done – or not done – constitutes sin, it was wrong and you now hate it as God hates it.
You and I know when we do things that are wrong – yelling at or being rude to someone, breaking a promise we don’t want to keep, protecting and promoting ourselves at the expense of others. Then we try to protect ourselves from feeling bad about it by trying to justify it, trying to make it seem less than it really is.
But scripture teaches that confessing our sins honestly and completely, without trying to gloss over it, or make excuses, is really the only way to spiritual health, and that brings us to the next step.
2) Contrition: Along with your confession of sin, with no attempt to excuse it or justify it, you also experience the sorrow that you have offended God and broken fellowship with Him. This doesn’t mean getting stuck in that mire of self-loathing. It means agreeing with God that it’s wrong, it’s bad, and we don’t want to have any part of it anymore.
3) Conversion: Resolving, deeply, to turn away from sin and turn towards Christ, coupled with a willingness to make restitution whenever possible. Then, that resolve has to be accompanied with actually doing something—following through with real change.
Repentance is a prerequisite, a necessary condition for salvation. But even after you and I are saved, we continue to sin. The Bible calls us to repent again and again as we are convicted of our sin by the Holy Spirit.