The whole reason Christ came into the world was to take upon himself the sin of the world. He who knew no sin would become sin. All the rebellion and hate and filth and sin and guilt of the world would be placed on Christ and the wrath of God would be poured out upon him. Consider Isaiah the prophet speaking of Christ -
... he has borne our griefs and carried our sorrows ... he was pierced for our transgressions; he was crushed for our iniquities; upon him was the chastisement that brought us peace, and with his wounds we are healed. All we like sheep have gone astray; we have turned-every one-to his own way; and the LORD has laid on him the iniquity of us all.
This would be a suffering far beyond physical suffering. Men, women and even children have been brave in the face of martyrdom. To say that Jesus was overwhelmed in the olive grove (gethsemane) because of the physical pain he was about to undergo would make him less brave than some children. This was both physical and spiritual. This was about the unique cup of suffering Christ came into the world to drink.
Isaiah 53 says that, it was the will of the Lord to crush him and bring him to grief and make his soul an offering for guilt. Could it be that the Father allowed Jesus to see inside the cup before drinking it? Perhaps he saw the spiritual sewage of humanities sins through the centuries and was feeling the dread of putting this on himself. Could it be that the Christ was overwhelmed at the reality that as he became sin he would be repulsive to the Father and for a brief time separate? Could it be that the very thought of being the object of the wrath of God produced a grief so enormous his body almost broke down in the garden praying to the point of sweating great drops of blood? These are mysteries we can only speculate about.
For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God. (2Corinth5)
What we are talking about here in theological terms is the mysterious work Christ came to do of substitutionary atonement. Our sin was somehow imputed (credited) to Christ. Like our sin was put on his tab. He was regarded by God as having all our sins and took the fierce punishment of the wrath of God that we deserve. He stood in our place, in our stead. And further, His perfect righteous life was imputed to us, so now, we who trust in Christ, are regarded by God as having the same righteousness as Christ Himself !!
There's a great scene in the movie I Am David where a young boy and an older man friend are in a prison camp. The little boy stole a bar of soap from the desk of the commander in charge. When it was discovered the soap was missing the commander lined all the prisoners up to search them and to execute the guilty. The boy had the soap in his pocket and discretely took it out and put it behind his back awaiting the sentence of death. The older man friend (Jim Caveziel) took the soap from him and put it in his hands. The commander discovered him holding the soap and unleashed the judgment upon him. Though he was innocent he was killed. It's a perfect illustration of what our Lord did for us. - Scott A