In Mark 8:13–21, Jesus warns His disciples in the boat to beware of the leaven of the Pharisees and of Herod — a hardness of heart that refuses to repent and dismisses all evidence of who Jesus truly is. Leon Pretorius shows that even the Twelve, despite their proximity to Christ and all they had witnessed, struggled with this same hardness. Yet Christ does not abandon them; instead, He patiently works to bring them to conviction and repentance, revealing that true understanding of who He is comes only as a gracious gift from God.