Summary: Hearing the word of God has a variety of reponses as Peter found out.
I. The Call for Repentance given by Peter
Now when they heard this, they were pierced to the heart, and said to Peter and the rest of the apostles, “Brethren, what shall we do?” And Peter said to them, “Repent, and let each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit. Vs. 37, 38
The first sermon of the church was about two minutes long. The results we are going to soon see is that 3,000 people became Christians. When Peter had explained what had taken place in the life of Christ, and the outpouring of the Holy Spirit, the people who had gathered asked an important question, one we should all ask, “What shall we do?”
There are two important question we should be able to answer in life. The first, Jesus asked of His disciples and also asks of us. When He was walking with them in Casearea Philippi Jesus asked them, “Who do you say that I am?” This is a question of significance because our whole destiny depends on how we answer that question. The second question we must answer is what they asked of Peter here, “What shall we do?” A wrong answer to this question, no matter how correct a persons belief may be, will lead to eternal tragedy. And Satan has worked his hardest to bring confusion to the minds of people when it comes to this question. We all know there is a plethora of wrong answers which have been given over the centuries to this question. We need only to go back to Peter’s comments in the first sermon to bring clarity to the question.
A. Conviction grips at the heart.
The Bible says after they had heard from Peter they were pierced to the heart. This is the only place in the New Testament where the Greek word used here, Katanusso, pierced, is used. It depicts something sudden and unexpected, something that stunned them. And they came to the realization that they were indicted by their guilt and behavior before God. There were several reasons for this:
1. They realized they had crucified their Messiah. They had been looking forward to the Messiah for decades, and now they came to the realization that the One whom they had hoped for they had now executed. That instead of welcoming Him when He walked among them, they had instead rejected and turned over to the Roman authorities to be executed.
1. They themselves had done it. Imagine, it would have been bad enough to hear that someone had killed the Messiah, but far worse when they found out that they were implicated in the complicity in the crime. Could you imagine a greater sin than to have killed the Messiah.
1. They now had fear of the Messiah’s wrath. Peter told them, unquestionable, the Jesus they had killed was now alive. Peter had quoted Psalm 110 (quickview)  which spoke of how the Messiah would now come and vanquish his enemies, and what greater enemy would he have then those who killed him.
1. They were devastated by what they had done. What they had done, they realized there was no way they could undo it. I think all of us know how that can happen in our lives.