Based on the scriptures he too wasn't sure why he died as he mistakenly thought that him being on the cross meant that God has forsaken him by not protecting him from his enemies. He should've known better than to go picking fights with others.
I think I heard that he lost faith in his father.
'Eli, Eli, lama sabachthani?' that is, 'My God, My God, why have You forsaken Me?' (Matthew 27:45 - 46).