the disciples having lived all this time with jesus and seeing his miracles should have had more faith in jesus and his teachings .they didnt only show little faith in his ability to save them....but they also showed little understanding of his teachings ...healings ...miracles.if they understood his teachings  they wouldnt have been so scared of dying...

In Jesus' time people who were physically unclean or who had a disease were considered to be spiritually unclean and could not participate in prayers or make sacrifices in the temple.The people in Palestine were afraid of lepers because they could infect healthy people with their disease, and they despised the lepers as people who must have committed terrible secret sins. so they were shunned and forced to live apart,Because lepers could not participate in worship,nothing could be worse than a lifetime away from worshipping God . most people believed that the disease was a punishment for earlier sins - not being able to worship God was the worst punishment people could imagine, so people thought the lepers must have done something horrible to be punished so severely for their whole lifetimes.That Jesus could cure a disease that no one else could even stop in its course shows that he was a true worker of miracles. That Jesus cured so many people who were prevented from praying and worshiping shows that his mission on earth was to reconcile people to God.