The burden and guilt of our sin was placed on Jesus
In addition to having to suffer physical pain on the cross, Jesus also had to suffer something far worse. All the sin of the world was, for a time, heaped on to Him. While that was happening, God the Father and The Holy Spirit withdrew from Him. He was required to bear the burden of the sin of the world entirely alone. While all of that sin was upon Him, God the Father and The Holy Spirit needed to show their utter unwillingness to be associated with our sin or to be tainted by it.
Jesus had never sinned or been guilty of anything throughout His eternal existence. Therefore it must have felt horrific to be directly associated with sin and to have all the sin, transgression and iniquity of all the world heaped on to Him and treated as if it was His own. In fact, as He hung on the cross and the guilt of all of it was put upon Him, God the Father and the Holy Spirit viewed Jesus as if He actually was sin. We are told that He was made "to be sin":
He made Him who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him. 2 Corinthians 5:21 (NASB)
God the Father and the Holy Spirit regarded Jesus as being so closely identified with our sin, and so covered by it, that they actually viewed Him as though He was sin itself in bodily form. In the eyes of God, He became sin personified and was defined by sin. He was also polluted and desecrated by it in a way that appalled Him.
It was also necessary for Jesus to be rejected and abandoned by God the Father and the Holy Spirit
For a time, while the sin of the whole world was pressing down upon Him, God the Father and the Holy Spirit had to separate themselves from Jesus. He was therefore left entirely on His own, just like the scapegoat that we referred to in Chapter 9. Even His Father and the Holy Spirit rejected Him during those hours. This was the time when Jesus reached the very lowest depths of His degradation, rejection and shame. He was, by this stage, totally forsaken, even by God. Notice what Jesus says from the cross about this feeling of abandonment. He says the words from Psalm 22 which King David had prophesied thatHe would say:
33At the sixth hour darkness came over the whole land until the ninth hour. 34And at the ninth hour Jesus cried out in a loud voice, "Eloi, Eloi, lama sabachthani?"—which means, "My God, my God, why have you forsaken me?"
Mark 15:33-34 (NIV)
It is impossible for us to overstate the significance of this abandonment. Jesus suffered indescribably through being rejected by and separated from His Father and The Holy Spirit. It had never happened before. He had been together with them in perfect harmony for all eternity past. The emotional pain of this sudden rejection and isolation, combined with the disgust and revulsion He felt at the sin of the world pressing down upon Him, probably caused Jesus more suffering than the crucifixion itself.
As well as His physical, mental and spiritual suffering, Jesus also had to die for us
When all these forms of suffering had been completed, it was time for Jesus to die. His death was essential. It had to go that far. He had to die, as well as suffer, in order to pay the full penalty for our sin. We are told this many times, but perhaps the verses which express the point most directly are in John's gospel. God caused Caiaphas, the wicked High Priest, who hated Jesus, to prophesy, (without realising it), that Jesus had to die for the nation (of Israel) and also for all of us:
45Therefore many of the Jews who had come to visit Mary, and had seen what Jesus did, put their faith in him. 46But some of them went to the Pharisees and told them what Jesus had done. 47Then the chief priests and the Pharisees called a meeting of the Sanhedrin. “What are we accomplishing?” they asked. “Here is this man performing many miraculous signs. 48If we let him go on like this, everyone will believe in him, and then the Romans will come and take away both our place and our nation.”
49Then one of them, named Caiaphas, who was high priest that year, spoke up, “You know nothing at all! 50You do not realize that it is better for you that one man die for the people than that the whole nation perish.” 51He did not say this on his own, but as high priest that year he prophesied that Jesus would die for the Jewish nation, 52and not only for that nation but also for the scattered children of God, to bring them together and make them one. 53So from that day on they plotted to take his life.
John 11:45-53 (NIV)