Three things can be seen as Peter delivers his first sermon:
1) The Clarity of God’s Approval- Peter emphasizes the truth that God approved Jesus- he empowered Jesus, Jesus fulfilled the Father’s plan, God raised him from the dead, God exalted him to his right hand, God gave him the Spirit. All of this shows that Jesus is the chosen, approved and exalted Savior and King.
2) The Tragedy of Human Rejection- Peter’s hearers however had rejected Jesus- they had crucified and killed him. We are like them- we have rejected Jesus and killed him in our hearts.
3) The Surprise of Gospel Grace- this combination leads to a place of desperation and a question of whether there is any hope. The surprise is that there is hope- if we will repent and believe there is a forgiveness and cleansing- there is life- there is the gift of the Spirit for us.