In the Bible, when hearing the word "doubtful" or "denial," there is only one particular person that comes up in mind. The only person that fits perfectly for these two words is one of Jesus' disciples, Peter. Peter was originally named "Simon," but after getting to know Jesus, Jesus changed his name to "Peter". Peter was a devoted follower, but had to be rebuked by Jesus a lot of times. Throughout the life of Peter, Peter goes through random greetings, godly scenes, and also denial.
In Mark 1:16-18, Jesus wonders around Galilee and finds a group of fishermen. He finds a young man by the name of Simon and tells him and the other fishermen to follow him. And immediately, they did as he said. After a lot of following, Jesus appoints his disciples and Simon, being one of them, is given the name "Peter" (Mk. 3:16). At this point, Peter's life has completely changed from a fisherman to a follower of some man with amazing persuasive skills. After going through a lot of miracles that Jesus performed, Peter knew who this person was. In Mark 8:29, Jesus asks his disciples who they think he was and Peter answers that He is Christ. Peter has complete confidence that He is the Son of God.
One day, Jesus and some of his disciples, along with Peter, went up to a mountain. When they arrived at the top, Jesus started to change in appearance and then a voice came from the clouds. It said, "This is my Son, whom I love. Listen to Him!" The disciples were simply astonished (Mark 9:2-7). After a few chapters, Jesus predicts Peter's denial when Jesus is about to die (Mk. 14:27-31). Peter is completely confident that he will never give up or run away from Jesus in any circumstance. However, Jesus is also confident that Peter will deny Him. Then the day came when Jesus Christ our Savior had suffered through pain. In Mark 14:66-71, Peter denies that he was a follower of Jesus Christ. Just as Jesus predicted, Peter has fallen into temptation and fear and trembled. Peter is ashamed and has nothing to say.
Peter's life was pretty much a life-changing story. He became a follower of Jesus Christ from a fisherman. Throughout his life, he witnessed and experienced many of Jesus' miracles and works. It is quite ironic to know that Peter denied Jesus because it seemed as if Peter knew Jesus the best, yet Peter ran away from Jesus when almost faced to death. I guess it is safe to say that he was a coward at the end, but we all know that Jesus still loved him regardless of what happened. Jesus died for our sins because He loves us so much. And that includes Peter's life long sins as well.