It isn't only the interminable scourging, which is done with endless inventories of instruments. The Bible has Christ suffering the weight of the cross as he climbs to Golgotha, but that is not enough for Gibson. He has stray soldiers impeding Christ every step of the way, bringing down their clubs and whips and scourges in something that cannot be understood as less than sadistic frenzy.
I write as author of a book ("Nearer, My God") in which I included a vision of the Crucifixion by an Italian mystic, Maria Valtorta. A learned priest cautioned against taking this liberty. "Valtorta seems to have solved the Synoptic problem that's been plaguing scholars for centuries, viz., the contradictions between Matthew, Mark and Luke. She has St. Dismas, the good thief, blessing Christ; Matthew (27:44) has him reviling him (Luke and Mark do not); she has Our Lord drinking gall mixed with vinegar (Mark 15:36 has him drinking just vinegar). I was amused to see Joseph of Arimathea boldly traversing the line of 50 soldiers and the angry Jews in order to get near the cross, since in Mark (15:43) we're told he 'took courage' to go to Pilate to retrieve the body."
This kind of improvisation is headlong in Gibson's "Passion." Still, the film cannot help moving the viewer, shaking the viewer, even as he'd be moved and shaken by seeing a re-creation of the end of Robert-Francois Damiens or one of those British sailors flogged to death. The suffering of Jesus isn't intensified by inflicting the one-thousandth blow: That is the Gibson/"Braveheart" contribution to an agony that was overwhelmingly spiritual in character and perfectly and definitively caught by Johann Sebastian Bach in his aptly named "Passion of Christ According to St. Matthew." There beauty and genius sublimate a passion that Gibson celebrates by raw bloodshed. The only serious question left in the viewer's mind is: Should God have exempted this gang from his comprehensive mercy? But that is because we are human, Christ otherwise.