Peter was a man easily irritated. Peter was rash, hasty, impetuous, self-confident and capable of great anger, full of vigor with a boisterous temper.

Peter, crippled by fear, denied the LORD - not once, not twice, but three times, yet on the day of Pentecost stood before thousands preaching a message of repentance, forgiveness and love.

"Let us remember that this sermon was delivered by a divinely-energized Peter, who now boldly warns those who several weeks earlier had taken part in the crucifixion of the Lord Jesus. He warns them that the day of divine judgment is near, and yet he gives hope because there is still an opportunity for repentance, salvation, and divine blessing. Let us listen well to these words, bearing in mind that thousands came to faith through this sermon."

Bob Deffinbaugh
Studies in the Bible

Peter is a vivid picture of a changed man. Changed by the power of the Holy Spirit to become a new man in Messiah. Bold in his faith, Peter willingly suffered persecution, imprisonment and beatings, rejoicing  that he was worthy to suffer for the Lord‘s sake.

John 21:18-19 speaks of the death of Peter. Church historians Tertullian, Origen, and Eusebius state that Peter was indeed stretched out by his hands, dressed in prison garb, and taken where he did not want to go. It is said Peter was crucified upside down because he felt unworthy to be crucified in the way that the Lord his Messiah had been. From an arrogant, cocky, man of thunder, he became a humble, willing, obedient servant of the LORD - even unto death.

As you stumble and fumble, fail and fall; groping and struggling day by day to follow the LORD, desiring to be all He has called you to be
... remember Peter.

(I did not realize [found the information while researching the life of Peter] there is extremely reliable evidence through church tradition and early church historians that the Gospel of Mark is actually the gospel of Peter. Peter is said to have dictated his discipleship with Jesus to John Mark. Mark was not present for Jesus’ ministry and did not have first hand knowledge of the extremely intimate details that are described in the book).