Then what was the crucifixion about?
In many ways it was about some Pharisees who were in power at the time (Annas, Caiaphas and that family) who were willing to sell out to Rome. It could be said that the ways of man ran head-on into the ways of God. Christ lived his life in obedience to the Father. He offered this life of obedience to God, an example for all of us that we can choose obedience to God over the ways of the world. At the beginning of his ministry, Christ was offered all that Rome and the High Priests had. He chose a different way, and one that led to his death, a death he freely offered. In choosing death, he chose life. That is his model to us: Obedience to God even when it leads to a horrible death.
Now, let's go back to sacrifice. In the Old Testament people offered grain, sheep, a goat--something of value to tell and show God how sorry they were for their sins and their promise to strive to do better. Other times, they laid their hands on a goat, telling of their sins, and then this goat was released into the wilderness, bearing their confessed sins with it. Today Christians (or at least Catholic Christians) offer to God what is most valuable to us--our life in Christ, and our determination to strive for the obedience that is Christ. Isn't our life in Christ the most treasured offering we have for God?
Putting this all together, did God ever punish a bowl of grain or anything else that was offered to him? Then it follows that He would not punish an offering of perfect obedience either. Christ offered up his life, he presented his life to the Father, and received his life back, more glorified than it had been before.
This is what the Crucifixion is all about.