In the past, God didn't judge people for what they didn't know. But now he commands all people everywhere to turn away from their sins. He has set a day when he will judge the world fairly. He has appointed a man to be its judge. God has proved this to all people by raising that man from the dead." (Acts 17:30-31 NIrV)
This concept is probably the most misunderstood concept in Christendom. The term translated "turn away from their sins" in Scripture is most often translated, "Repent!" I've heard preachers yell it. I've watched priests give assignments to prove it. I've listened to people say it, then immediately follow it with another statement: "Now, you're going to mess up again. Everybody does. God doesn't expect you to be perfect. You just need to be sorry for your sin." Nothing could be farther from the truth.
The greek word μετανοέω (metanoeō) means "to change one's mind or purpose." In other words, it's not about feeling bad. It's about seeing things differently. Something about the way you look at "potholes" (temptations) still holds it's appeal. It still looks fun. You still want to do it. Repenting means you look at it differently now. You look at it through God's eyes. You see that His design (staying on the path) is far better than these distractions you've been wasting your time on. Repentance means you want to walk with God.
In our pothole illustration, you were hurt at the bottom of the hole. You look at the floor of the cavern in which you are stuck. You look around at the walls trying to find a way out. You even look up - maybe even seeing Jesus up top - and you want out because it hurts. This is not repentance.
Then you start thinking about the series of events that got you where you are. You remember that you were walking down the path when someone pointed out the pothole to you and said, "Let's go jump in. I've heard they're a blast!" You remember walking up to the edge of the pothole to look down. Peering down the black hole, you remember wondering what was at the bottom. You remember all the voices talking to you about the pros and cons of jumping in the pothole. You also remember one clear voice saying, "That's not the path I designed for you. Someone put it there to hurt you. Please don't go. I don't want you to die."
Suddenly, that voice makes sense to you. You realize that was the voice of God. Not only do you realized the love that God has for you, but you also see temptation (potholes), sin (jumping in), and death the way He does. You want no part of it - ever. You want the path God had designed for you. You don't blame God for your situation. You don't blame other people for trying to get you to jump in. You blame the design-twister who dug the pothole to trap you and your friends.
You don't just want out. You want to try again...this time listening to His voice, walking the path He designed and built, walking with Him. That's repentance. Jesus is willing to help anyone who repents.