Does the suffering Christ went through pay for our physical healing only, or also our spiritual healing?
Consider these two passages:
"But He was wounded for our transgressions,
He was bruised for our iniquities;
The chastisement for our peace was upon Him,
And by His stripes we are healed" (Isaiah 53:5).
"Make the heart of this people dull,
And their ears heavy,
And shut their eyes;
Lest they see with their eyes,
And hear with their ears,
And understand with their heart,
And return and be healed" (Isaiah 6:10).
Both passages refer to being healed. In both passages, the Hebrew word translated into the English word heal is the same.
Look at the context of the second passage. It is quoted by Jesus Christ in Matthew 13:10-17 where He talks about the fact that His disciples can hear and understand but not Israel as a whole. In other words, He was talking about calling, and the difference in understanding between those who are called and those who are not called in this age.
The context of Isaiah 6:10 is calling, conversion, and spiritual healing, not physical healing. God is saying that the people are blinded so they cannot see and understand, lest they be spiritually healed. When we are called and converted, God begins a process of healing us spiritually, healing our character, and this is done through God's Holy Spirit.
Yet that same word "healing", in both English and the original Hebrew, is used in the passage that says that by Christ's stripes we are healed. This seems to indicate that the suffering Christ endured not only paid the penalty of suffering that comes from physical sicknesses and problems that come from breaking the physical laws of health, but the suffering Christ endured paid the penalty of suffering we incur by our spiritual sins, in other words, the spiritual damage to our character, caused by sin, that causes both the sinner and those around him to suffer.
The penalty for our sins is death (Romans 6:23). But that is not the only penalty. We also pay a penalty of suffering for our sins. Sin produces suffering. It damages our character. It creates contention, strife, and unhappiness. Satan and the demons suffer because of their sins and sinful nature. They pay that penalty even though they do not die.
Before Lucifer sinned, he was perfect in his ways. "You were perfect in your ways from the day you were created, Till iniquity was found in you" (Ezekiel 28:17). But when Lucifer sinned, something happened to his mind. It became perverted, twisted. "...You corrupted your wisdom for the sake of your splendor..." (Ezekiel 28:17). He became Satan the Devil, an enemy of God. Likewise, as Mr. Armstrong pointed out, when Adam sinned, something happened to his mind. He began to develop wrong character, and that character led to sin and more sin, and sin has led to all the evils and suffering of this world.
So for humans, the penalty of sin is twofold: 1) suffering, resulting from the bad consequences of our sins, and 2) death. When Christ suffered and died, he paid both penalties. By letting his blood be shed, He paid the death penalty of our sins so we don't have to die. This makes it possible for us to be given eternal life and live forever. But it would do us no good if we lived forever but remained slaves of our evil human nature and continued to make ourselves and others miserable with suffering by our sinful choices. So Christ also sacrificed His flesh, and allowed Himself to be scourged and beaten and allowed his flesh to be torn so that He suffered, and thus He paid the penalty of suffering for our sins. This makes possible our spiritual healing, which God does through His Holy Spirit, to clean up our character, so we do not have to continue to suffer the consequences of sin. It also makes possible our physical healing so we do not have to continue to suffer the pain and weakness of physical sicknesses and injuries brought on by breaking physical laws of health.
The process of breaking physical health laws, damaging our bodies, and suffering pain and weakness as a consequence of breaking physical laws is a parallel of the process of breaking the spiritual law of God, damaging our character, sinning, and bringing upon ourselves the suffering that comes from sin. That suffering can come from conflict, contentions, jealousies, violence, hatreds, and every type of evil, all of which come from breaking the spiritual law of God. The suffering Christ endured paid the penalty of suffering for violations of physical health laws and the spiritual law of God, so that both can be forgiven. This makes possible the forgiveness of both physical and spiritual sin so that God can heal us physically, by repairing our bodies, and heal us spiritually, by cleaning up our character and developing the character of Christ in us by the Holy Spirit. Both are necessary to remove suffering from our lives, which is one of the penalties of sin. Christ suffered to pay that penalty so we do not have to continue to suffer in this life or in the life to come. Then He died to pay the death penalty of our sins so we can live forever.
Here are links to related sections in Preaching the Gospel:
Passover -- the Sacrifice of Christ, Chapter 2