Thoughts on Question 9 / Luke 15

When God forgives our sins, what happens to them? (the sins that is)
Are they forgotten? Is it like they never happened?

Yes and no.
It’s easy to think that when we get forgiven, our sins go unpunished.
But this just isn’t true.
For God to be just, He must punish sin.
In fact, it would be hard to define a word like “justice” if sin could simply be forgiven and forgotten.

Since sin must be punished, you’re in a pretty tough predicament. You’re only hope is a divine pardon and a substitute who doesn’t have his own punishment to undergo, to take your punishment upon himself.
That’s where Jesus comes in. That’s what the cross is all about. Jesus paid the price for your sins. He was punished for your transgressions. God’s perfect justice is accomplished.
So, in one sense, the answer is yes, when God forgives your sins, it is like you never committed them. It’s as if, for you, they never happened.

But he was pierced for our transgressions, he was crushed for our iniquities; the punishment that brought us peace was upon him, and by his wounds we are healed.
Isaiah 53:5

…for all have sinned and fall short of the glory of God, and are justified freely by his grace through the redemption that came by Christ Jesus. God presented him as a sacrifice of atonement, through faith in his blood. He did this to demonstrate his justice, because in his forbearance he had left the sins committed beforehand unpunished – he did it to demonstrate his justice at the present time so as to be just and the one who justifies those who have faith in Jesus.
Romans 3:23-26

God made him who had no sin to be sin for us, so that in him we might become the righteousness of God.
2Corinthians 5:21

In fact, the law requires that nearly everything be cleansed with blood, and without the shedding of blood there is no forgiveness.
Hebrews 9:22