My little children, I am writing these things to you so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous; and He Himself is the propitiation for our sins; and not for ours only, but also for those of the whole world.
— 1 John 2:1-2
It’s is commonly understood that propitiation is the atoning sacrifice that appeases God’s wrath. That’s the definition I’m going with here. Looking at this passage, we can conclude one of two things. God's wrath was satisfied for some or for all. Those who think it’s for all take “whole world” prima facia and say God loved the whole world and bore the sins of every man. Those who say it’s only for some look at the context and see the “our sins” as John’s immediate audience, and “whole world” as indicating that it’s just not his audience, but others throughout the world.
My argument against the former is that if God’s wrath is satisfied by His Son’s sacrifice, then He would be unjust for sending anyone to hell. It would be akin to someone paying off my house in full, yet the bank foreclosing on my house. That would not be just.
So it’s best to see “whole world” as referencing people throughout the world, as opposed to every single person in the world.
I agree with one of your conclusions: “if God’s wrath is satisfied by His Son’s sacrifice, then He would be unjust for sending anyone to hell. It would be akin to someone paying off my house in full, yet the bank foreclosing on my house. That would not be just.”
It would also be totally unjust for God to choose to not save some people that are just like the people God does save.
This has to do with the huge topic of atonement and the one part of Christ being the atonement sacrifice for all people.
First off: Just because Christ is the atonement sacrifice for all people does not mean, atonement has taken place for all people. There is much more to atonement than just the sacrifice itself. Atonement is a process, all mature adults can go through which is much more than just a onetime event.
I am not a big fan of the English word “propitiation” used to translate the Greek word “hilasmos” which is also translated: atoning sacrifice, expiation and reconciliation. The previous description of Jesus is an Advocate.
If you insist on using “wrath”, we need to realize this is the Father’s “wrath” toward both Christian and non-Christian, children.
This is the absolute greatest Loving Father who is very willing (like all wonderful parents) to forgive their children, but that is not the only responsibility of a Loving parent toward their rebellious disobedient child. Really great Loving parents will also see to Loving just/fair disciplining of their children if at all possible. The problem is not with the Loving parent or God, the problem is with the rebellious disobedient feeling comfortable standing reconciled by the parent (or God).
How did the first century Jews who went though the atoning process for their sins understand it:
Atonement is one of those religious concepts which is best understood through experiencing it, then trying to explain it. Unfortunately, the new Christian is filled with ideas about atonement prior to experiencing it, so they are brain washed into trying to feel something that does not happen and quenching what should happen.
One of the advantages the Jews before Christ’s sacrifice had with atonement was personally going through the atonement process for very minor sins (unintentional sins). Lev. 5 explains why, sinners goes through in the atonement process and might be a good place to start. There is also the advantage of the Lev. 5 atonement being for the individuals personal and actual sins.
We might be able to take the atonement process for very minor sins and extrapolate up to what it could be like for rebellious disobedience directly towards God requiring death for the sinner with no atonement possible under the Old Law.
It would be best to imagen yourself as a first century (BC) Jewish man who just accidently touched a dead unclean animal. If you are real poor you are going to have to work an extra job help someone else for money to buy a sack of flour. If you live in the city and have money you are going to have to go out and buy a lamb and some grain to feed it. You are not a shepherd, so you will have to drag or carry a balling, thirsty and hungry lamb to the altar. You get up early to hike into Jerusalem wait in line for hours to hand the flour or lamb to the priest and watch them go through their part of the atonement process which if all is done right will result in God forgiving you and you feeling forgiven.
There is more to what and why this happens which we can find in Lev. 5:
5…they must confess in what way they have sinned. (which we need to do in the atonement process)
6 (The sacrifice) As a penalty for the sin they have committed… Here the reason for atonement is given “as a penalty” (punishment but better translated disciplining).
If the sacrifice was made as a “payment” for a sin: these sins are all the same and God considers all people the same, so the sacrifice would need to be the same (a lamb for all or doves for all or flour for all) but the sacrifices are not the same. The different values of the sacrifices, is an attempt to equalize the hardship/penalty (disciplining) on the sinners and does not suggest a payment being made to God especially a payment to forgive a sin. God’s wrath would not be satisfied with a bag of flour to forgive sins.
The intention of the sinner going through all this, would be, all the benefits that come from being Lovingly disciplined.