One of Bart Ehrman's stock examples of alleged discrepancies in this Gospels is his contention that Mark and Luke present contradictory accounts of the Passion. I'll make a few observations:
i) Part of the problem is with his illogical assumption that if one account includes information not mentioned in another account, that must be fictional or unhistorical.
ii) It doesn't occur to Ehrman that if someone is in a state of extreme physical and emotional distress, that person may well be subject to mood swings. Surely that's a commonplace of human experience. People in that condition may oscillate between hope to despair. It's perfectly realistic for the same person to have conflicting feelings–especially when traumatized. It would be surprising of Jesus did not experience a gamut of emotions during this crisis.
iii) In addition, a subjective feeling of divine abandonment is entirely consistent with an objective reality of divine provision. That's a common motif in the Prophets and Psalms. A sense of utter desolation doesn't mean the sufferer has in fact been deserted by God.