A question that some skeptics ask about Christianity is why God doesn’t just forgive everyone. Why couldn’t He just let it go? Why did Jesus have to come and die? Why require people to ask forgiveness and follow Christ in order to be saved from eternal punishment? Is God just making up arbitrary rules and having us jump through pointless hoops to get forgiveness?
It’s important that we Christians have an answer for this, because it’s a foundational matter. Here is my reasoning on the topic.
A God that simply "forgives" everything that people do has no standards and cannot be said to be good, or even a moral authority. Because God, as the Creator, is indeed a moral authority, it is impossible for Him to have no standards, and thus He must punish evil, not ignore or "forgive" it as standard policy.
Also, forgiving evil without requiring anything is no different from accepting evil. And acceptance of evil is evil itself. God's character does not allow Him to accept evil. God is inherently good and does not change, thus He cannot accept evil. Because God cannot accept evil, sin inherently and unavoidably separates mankind from God.
Full forgiveness includes reconciliation and thus cannot be one way. God forgiving someone's sins without them seeking forgiveness and restoration would not result in reconciliation. They would remain enemies of God. God wants us to be reconciled to Him, and thus requires our actions in seeking forgiveness so that full reconciliation can occur.
Providing forgiveness that does not involve reconciliation would encourage people to remain enemies of God instead of reconciling with Him. Since we were made to be in right relationship with God, a relationship with God is the highest good for us. Providing automatic forgiveness would actually encourage that which is not for our good. It would not be loving of God to encourage us not to seek relationship with Him when that relationship is our highest good.
Because God is both just and loving, He wishes to extend mercy to those He loves and be reconciled to them. But these two attributes – justice and love – are both integral parts of God's character and cannot be satisfied alone. The solution to man’s sin and separation from God had to involve both justice and mercy. The debt had to be paid, not merely ignored, for justice to be satisfied. And yet if the debt were to be paid by the one who owed it, it would result in their separation from God forever, denying God the relationship He desires with them and which is for the person's good. Thus, there had to be a substitute who could pay the debt on behalf of each person.
Not just any substitute will do, however. The sin was against an infinite God, which requires infinite payment. And thus only God Himself could pay the debt. Yet the sinner was human, and being a substitute for a human requires being a human also. The debt had to be paid by one who could actually represent mankind because he was one of them. Also, only someone sinless could pay the debt, because if he had sin of his own, his payment would only cover his own sin. For a substitution to work then, the substitute had to be a sinless man who was also infinite.
Only God in human flesh could pay the infinite debt for mortal man and satisfy both justice and mercy. And yet to partake in the plan of substitution, each person must opt in by willingly choosing to seek forgiveness so that full restoration can occur with God and relationship can be restored between them. There is no other way.