WHY was Jesus cricified?

[John V]

In respect to God, we'd be forgiving each other because we were forgiven by him, but with respect to each other, we are to forgive without expecting any compensation or punishment.

So, why couldn't God simply do that with us? Why does there need to be some sort of atonement to seed the whole process?

Because God's sense of justice requires it.

And before you say something about God's nature or forgiveness without atonement isn't "just": how does one person's atonement pay for the sins of other? What did God gain from it? Jesus didn't really atone for anything anyway, because he's sitting in heaven. There was no sacrifice; there was no atonement.

How does saying "I'm sorry" atone for your wrongs to one person, but not to another? How does paying a fine to the state atone for going through a stop sign? How does prison time atone for anything anyway - former convicts are now free people?

ETA: How does one atone for murder?

If my child A hits child B and I tell child B to simply forgive A, does that mean that I must likewise do so, and cannot punish A? If I do punish A, does that mean that B must also punish A in the same manner?

If a president pardons one criminal, why doesn't he simply pardon them all?