If someone wrongs another—say, I steal your car—there are three things that I must do to make our relationship right again. And even after I do those things, you might choose not to forgive me.
The first is that I must receive punishment for my crime. I must serve my jail time or be put in the stocks or take twenty lashes or whatever the law says must be done.
Second, I must make restitution. I must not only return the car to you, but I must also pay you for your time without your car. Let's say you had to use a rental car. Then I would have to reimburse you for the costs of the rental.
Lastly, and I suppose most importantly, I must apologize and mean it. I must regret my bout of kleptomania and try not to do it again.
Likewise, if a man has wronged God—say, he spends his life as if it were his own and not God's—there are three things he must do to make his relationship right again.
First, he must take the punishment for his crime. And the only punishment suitable for someone who says to God, "I don't want you in my life," is just that: to live forever without God. In other words, damnation.
Second, he must make restitution. He must not only return his ill-used life to God, but he must give to God the life that he should've been living in the first place: the perfect, holy, and blameless life.
Lastly, and most importantly, he must apologize to God for trying to live apart from Him. He must mean what he says and also not live as a rebel anymore.
There seems to be quite a lot of hiccups in this process as I'm sure you've noticed. Quite a lot of impossibilities.
First, nobody wants to take the punishment he or she deserves. Hell? Who wants that? Second, no one can give back to God a perfect, holy, and blameless life because nobody can live perfectly even if he or she were given a chance to start over. Lastly, while we might apologize to God every day of our lives, that doesn't change us. We're still going to be selfish, both in thought and deed. Again and again and again. It's the way we are. We don't spend our lives as God would want us to. As Christ did.
And therein lies the cure.
First, Christ took the punishment for our crimes. He took our damnation upon himself through his death.
Second, he made restitution for our failures by living the perfect life and by being the perfect human. That life reimbursed God for the life we couldn't live.
Third, he made and is still making the perfect apology to God on our behalf. This happens when we raise the white flag and give the controls over to Christ. At that moment God looks down into our hearts to see if our rebellious days are over and instead of seeing a self-absorbed little insurgent, he sees Christ there forever apologizing, forever presenting a changed heart, forever teaching us the way to live like children of God. And God accepts the apology.
The relationship is made right.