Have you ever had to give a presentation? It's not easy to speak to a crowd. Peter wasn't very well educated. He was just a fisherman who was unsure of himself enough to deny Jesus in front of people around him when put under pressure. Now here he is standing and speaking in front of thousands of people. What was the reason? God had given the Holy Spirit to his disciples and given them a new start.
What does he tell the people about Jesus now? He told of Jesus miracles and proof that Jesus was the Son of God, and reminded them that they had killed Him. Peter also proclaimed that God raised Him from the dead, proving He was the Son of God as promised by God in the early scriptures of the Bible.
Jesus has carried out perfectly what God had sent Him to do and now He sits at Gods right hand in a position of power and authority. He sent the Holy Spirit to continue His work in our hearts.
This was Gods purpose and plan since he beginning. God is sovereign and in control, yet those evil men who killed Jesus were all part of what happened. How can this be? Did they take credit for being part of Gods plan? Of course not! They were cut to the heart with guilt. They realise they were being held responsible for putting the Son of God to death. They didn't argue or shift the blame, they knew they had killed Gods Son... The very Messiah they were looking for since the Bible began.
Do you ever feel guilty or do you shift the blame? The Holy Spirit is given to convince us of our sin so that we are cut to the heart with guilt. This is so that we turn to God and ask if there's a way to be forgiven. And there is! If we are sorry and turn from our sin, He is willing to forgive us, remove our guilt and change our hearts. The Holy Spirit can make us new people from the inside out.
Peter pleads with the people to do something about their situation. It was an urgent plea, that each person would make themselves right with God. At this time, 3000 of those who had wanted Jesus dead were saved and being baptised.
We didn't crucify Jesus, but if we reject or despise Him, it's just as bas as if we had.