I used to think (as you did) that "the atrocities against Jesus [...] are in fact instigated by the religious parties." I was taken in by Pilate's whole hand-washing gesture.
Then it was brought to my attention that Pontius Pilate acts in his own self-interest in condemning Jesus to death by crucifixion. He freely admits to all that he considers Jesus innocent: "I find no fault in him" (or words to that effect). Herod also finds Jesus blameless (just "crazy"). And yet Pilate still has him "scourged" to mollify the crowd (does that seem fair to you?), and finally agrees to crucify him after Caiaphas taunts him with, "If you do not you are no friend of Caesar." The potential for displeasing Caesar was always on Pilate's mind, as his conversation earlier in the film with his wife was clearly meant to indicate. So, Pilate sends a guilt-free man to the cross simply to save his own career/life and/or prevent rebellion. Yes, it was the Temple Priests who brought Jesus to Pilate initially, demanding Jesus' death. But Pilate was the sole arbiter in the end, something he was fully aware of and which he even stated to Jesus. Pilate's complicity in the death of Jesus is undeniable.
Remember what Jesus said to Pilate? "He who handed me over to you has the greater sin." Not "the sin," or "the only sin," but the "greater" sin.
Make of that what you will... :-) Convinced me.