It is not clear whether you are referring to the actual passion of Christ or if you are asking about a reflection after watching the movie "The Passion of the Christ."
Either way, as a Catholic, one always feels a very strong sense of pain only imagining the horror of the occasion. In Catholic school teachers are very committed to instilling a sense of guilt, at times, by reminding students that all of the sacrifices that Jesus endured were done to cleanse us from our sins.
The passion was a very horrid execution: The rules of the times of Jesus were barbaric in the treatment of those condemned of high treason, not much differently like the prosecutions for high treason that were in place during the Dark and Middle ages.
During these executions the accused suffered from extreme public humiliation and were given sub-human treatment which included whipping, dragging, pushing, hitting, slashing and, ultimately, the final crucifixion. To top it all, their bodies were left to rot at the cross so that the public could see the vultures gnawing and picking at the bodies. That was SOME lesson on how NOT to revolt against the system ever again.
Therefore, thinking that a man who was otherwise a good man endured all this punishment leaves a strong feeling of sadness in any believer.