There is some significant debate over whether or not it was actually Peter who wrote this letter or someone writing in his name, tapping into his tradition. I believe there is enough evidence to support Petrine authorship and that it is far more helpful to read and interpret the book as though he wrote it.
So, who is this man? His birth name is Simon (or Simeon). He is a Galilean fisherman from the town of Bethsaida, and he is the brother of Andrew. His brother introduced him to Jesus of Nazareth when they were young adults. A survey of Peter's life yields six key "chapters." If you'd rather listen to a message on this, click here.
Chapter 1: Young, Passionate, Over-Zealous Faith.
This chapter covers basically the entire ministry of Jesus and his disciples before Jesus is arrested in the Garden of Gethsemane. Simon quickly becomes a very close friend to Jesus, and it is clear that along with James and John he is in Jesus' "inner circle." Jesus gives him the name "Cephas," which means "Rock." The Greek word for rock is Petros; thus, he is commonly known as Peter. He is also the most vocal and passionate of the disciples - he clearly wears his heart on his sleeve. Luke shows him falling at Jesus' feet when they first met, crying "Depart from me, Lord! For I am a sinful man." Peter witnesses many miracles first hand. He is the disciple who recognizes Jesus' true identity first, saying he is the Christ (that is, the "anointed one"), and the "son of the living God." Peter walks on water with Jesus (for a moment). He is there at the transfiguration. Notably, Peter repeatedly and loudly states his overwhelming commitment to Jesus, and to the victory of Jesus. He rebukes Jesus for his passion predictions (that's no way for a king to act!), and promises that he will never leave or deny Jesus. After all, as Peter is quick to remind us, he has "left everything to follow" Jesus. His faith is fueled by the miraculous, full of passion and fervor, and believes that, by virtue of Jesus, he'll be part of the new government of Israel when the Anointed One seizes his rightful throne. He always treats Jesus like a king, including refusing (initially) to have feet washed by the Christ.
Chapter Two: Disappointment, Denial, and Shame
This is a short chapter in Peter's life, but a very dark one. When Jesus is arrested and shows no signs of struggle (he even stops Peter from defending him), Peter's expectations of being a General in Jesus' army are quickly dashed. It seems he had daydreamed this victory so many times that he lost sight of who Jesus really was - he never understood a passion prediction. So, following at a distance, Peter is confronted three times regarding his connection to Jesus. He vehemently denies it - and, while it was lie, perhaps his heart and mind really felt as though he had never really known Jesus. The Jesus he knew was the one he created in his his daydreams: a victorious king, reigning in Jerusalem, freeing the Jews from the hand of Rome. All of Peter's young, passionate, over-zealous faith comes crashing down.
Chapter Three: Restoration
The final chapter of the Gospel of John recounts a scene after the crucifixion and resurrection of Jesus, where Jesus approaches Peter on the shore and asks "Do you love me?" Three times in three ways (the English does not reflect the variety of Jesus question). Peter responds with a passionate "yes" each time - the relationship is being rebuilt. In this moment, Jesus places this man who turned his back on him in a moment of doubt in the place of leadership and purpose for his followers. It is restoration at it's best: the grace of Christ makes Peter more than what he was before.
Chapter Four: Power and Authority
Peter then naturally becomes the leader of the fledgling group of Jesus' followers. And, after Jesus ascends to heaven, they follow his instruction to wait. In an amazing moment, the Holy Spirit comes upon the disciples, and they are filled with power and boldness not their own. Peter is the shining example of this: he delivers an impromptu speech to the crowd and 3000 become believers in Jesus and set themselves aside through baptism. Peter seems to be walking in the Spirit's power the most fully of the disciples, as Acts shows him undaunted by imprisonment; his shadow has healing power, he raises a girl from the dead, he heals a paralyzed man. Peter is quick to say this power is not his own, that it is the authority of Jesus. This humility is easily connected to the life experience of over-zealous faith, shameful failure, and merciful restoration.
Chapter Five: Mistakes and Lessons
Having been restored and filled with the Spirit does not mean Peter is now infallible. The key example of this is his confusion and wavering regarding the inclusion of the Gentiles into the Jesus-following community. He receives a vision which seems to indicate they should be included by virtue of faith and grace; and yet within a couple years it's clear he's re-considered. Paul recounts the necessity of rebuking Peter face to face for his inconsistency and lack of clarity on this key issue - the heart of Jesus' purpose in the world is at stake. Peter must learn. Based on the words of his first letter, it seems he has. All Christians must continue to learn as he did - even if the miraculous power of the Holy Spirit is directly present in your life!
Chapter Six: Martyrdom
It is said that Peter was executed by Nero in the year 64, and that his request to be crucified upside down was granted. Peter's last act was his greatest: he shows a full understanding that his Lord's kingdom is "not of this world," and that true victory comes not in the brandishing of the sword (as Peter did in Gethsamene so many years beforehand), but by total sacrifice.
May it be that followers of Christ today would see their own growth in chapters similar to these. We start with passionate faith, we experience loss or frustration paired with failure and shame (and essentially walking away from Jesus), we are granted restoration, we receive true power because now we're not trying to do it "on our own," but look to God for everything, we continue to grow and learn, and finally we live a totally surrendered life.