A friend forwarded an email to me describing how each of the apostles died. Among them, Peter was crucified upside down on an x-shaped cross. Church tradition has it that Peter requested to be crucified that way because he felt unworthy to die in the same way Jesus died. He was totally convinced that Jesus was who he claimed to be, the Son of God. Peter was willing to die for his conviction in the belief that he (Peter) will soon be joined to Jesus in eternal life.
Yet Peter was not always the picture of bravery we see here. In Matthew 14 we read that Peter trusted Jesus enough to step onto the water, but soon got scared and began to sink. Matthew 14:29-31: "... Then Peter got down out of the boat, walked on the water and came toward Jesus. But when he saw the wind, he was afraid and, beginning to sink, cried out, "Lord, save me!"Immediately Jesus reached out his hand and caught him. "You of little faith," he said, "why did you doubt?" "
Perhaps an more even poignant example of his lack of bravado was his denial of Jesus even after Jesus had told him that he would deny Jesus; not once, but three times. When Jesus was arrested and charged with blasphemy Peter was terrified and tried to slip away. Matthew 26:73 says "After a little while, those standing there went up to Peter and said, "Surely you are one of them, for your accent gives you away." Then he began to call down curses on himself and he swore to them, "I don't know the man!" Immediately a rooster crowed. Then Peter remembered the word Jesus had spoken: "Before the rooster crows, you will disown me three times." And he went outside and wept bitterly."
If someone of so little courage can in the end stand up for his conviction even after his mentor is gone, I cannot think of any greater demonstration of faith. Moreover, every one of the apostles stood up and died for their belief after the resurrection. Not a single one escaped persecution; not a single one caved in.