I'll use my own words so just understand that what I say is not intended to offend anyone based on differences in extent of the atonement, only to show what it did.
His death was part of the plan for our redemption. It was God's will (and I'm including Son and Holy Spirit) that Jesus atoning death would be satisfactory to God, enabling him to forgive repentant sinners without being inconsistent within his own nature, which puts an equally high priority on justice, as well as mercy.
There are multiple aspects involved here and no single verse has all aspects yet each aspect is supported by verses. This by the way is the way it is with all Christian doctrines which have a developed theology or a confessional nature.
Death of the sacrifice was required and proof of death was by the shedding of blood. This stops all nonsense of punishment not going all the way to death being redemptive. Anyone who says that "by his stripes we are healed" and then takes that and says that proves that a whipping would be sufficient for example should never be trusted to interpret scripture. Scripture says that the life is in the blood (we know medically that that is metaphorical) but the meaning is clear: violent, deliberate death actually had to be inflicted upon the sacrifice and the end point had to be death. Death is what the law required and it is what the sacrificial system required.
We can only speculate on why Jesus death was sufficiently propitiatory and satisfactory to God but we are told in scripture that it was. Also, scripture seems to indicate more was going on in the atonement than we are directly told. Theologians speculate that Jesus agony over his death had to be more than the prospect of the physical because many Christian martyrs actually suffer their physical executions almost cheerfully. It is surmised that Jesus was contemplating the taking on of our sins, as scripture clearly teaches, that caused this extra angst for him.
All of our actual ability to come to God or stand before God is based on this work of Christ. God is allowed to ask for any "conditions" or acts in addition that he wants and he is allowed to demand ongoing obedience or holiness as he chooses. He is allowed to still have life be as he ordered it with physical death, subjection to violence, disease, accident, vanity of life and so on without answering to you that that indicates some deficiency in the atonement.
Thank you for taking the time to explain your position.
The way I understand your words is that there is no specific reason for Christ to have died except that this was God's plan (His death was not in our place as we die, but was required of God and is something to accept as true).
My point is that Penal Substitution itself does not depend on Christ dying. Christ, according to that theory, propitiated God's anger towards us by experiencing that anger instead of us experiencing that wrath.
I am in no way claiming that you do not believe Christ had to die. But I am saying that His death is not necessary strictly under the Penal Substitution Theory of Atonement.
I do not assume the Penal Substitution Theory to constitute your entire belief system or faith.
Here are a few things to consider:
1. God presents with two types of death. One is physical death which is appointed all men followed by the judgment. The other is the lake of fire " the lake that burns with fire and sulfur, which is the second death").
Christ suffered a physical death. Christ did not suffer the second death. He was not cast into the Lake of Fire.
Penal Substitution theorists hold there is another type of death - typically a separation or break in fellowship with God - that Adam experienced in the Garden and Christ experienced in the Cross. Viewing death this way is a mistake.
In Genesis Adam was cast out of the Garden, and the Garden was a unique place where Adam enjoyed fellowship with God. BUT Adam was not originally in the Garden, originally in that state of fellowship, and when he was cast out he was returned from whence he had been taken. This casting out from the Garden was not the first time Adam was in that situation.
Even if Christ experienced a separation from God (an idea I reject) the second death is not defined as separation. It includes separation, but it is a specific place - a place prepared for Satan and his demons.
2. Christ experiencing death cannot, under Penal Substitution Theory, be God's punishment for our sins that we would suffer because we experience death and Christ did not experience the second death. The best it actually does is say Christ experienced something that God accepted in place of the punishment we would have suffered (satisfaction, not substitution).
The issue remains that we still suffer the wages of sin (death). If this is even a part of our punishment for sin by God then God is unjust to require it twice (once from us, once from Christ).
3. We are still left with the fact that Penal Substitution Theory has no actual use for the Cross (specifically) or for Christ's death. People affirm Christ had to die, but their reason is "mystery", or as you said
"God is allowed to ask for any conditions or acts in addition that he wants and he is allowed to demand ongoing obedience or holiness as he chooses."
The reason is that is what God wanted, not that Christ's death actually redeems man in any significant way. God just decided His Christ must die.
That is what I mean when I say that the Penal Substitution Theory of Atonement has no use for the Cross or for Christ's death. Had God decided that Christ should suffer by being stoned and then ascend without dying the Penal Substitution Theory would not be affected at all.
Classic Christianity, however, depends on Christ dying on a Roman cross. Christ had to die in order for man to be saved. Not because of some mystery in God's plan.
Another difference is how you view the sacrifice system. You assume it was as ANE pagan sacrifices. It was not. Sacrifices were not made, under the Old Covenant, on an altar. Priests were not punishing animals. Sins were not forgiven. The importance was in the shedding of blood which was to cleanse. It was a preparation for the people (symbolically, foreshadowing the cross) which covered sins (looking to actual forgiveness) for God to "dwell with His people'.
Penal Substitution Theory makes assumptions and reads even into the levitical system.