The Greek word for "repent" means to change one’s mind or purpose, according to Vine’s Expository Dictionary of New Testament Words--and always, except in one specific passage, it refers to repentance from sin. When we repent, we change our mind about sin, agreeing with God that it’s wrong--and we change our purpose, turning away from that sin in His strength.

From the first of His ministry, Jesus taught that we must repent. In Matthew 4:17, He preached, "Repent, for the Kingdom of heaven is near." In Mark 1:15, Jesus said, "Repent and believe the good news!" Notice that repentance comes before belief. In Luke 13:3 and 5 Jesus says twice, "unless you repent, you too will all perish."

Those who are lost need the Holy Spirit to convict them of sin and to lead them to repentance. Paul said in 2 Corinthians 7:10 that it is godly sorrow that brings repentance that leads to salvation. When we pray for the lost, one of the most important things to ask is that God will send His Holy Spirit to convict them of their sins, for without the conviction of sin, to them the cross has no meaning, to them our Savior seems to have no purpose.