In Mark 8:11-21, Jesus turns his face away from the Pharisees for thier hardness of heart. At the same time, as part of his ongoing preparation of the disciples for what is ahead at Calvary and his crucifixion, he cautions the disciples for their apparent unbelief. What we learn is that it will ultimately take the Holy Spirit to change their hearts (and ours) in order for them (and us) to believe and move past the crucifixion and towards a true Spirit filled life.