“Let all the house of Israel therefore know for certain that God has made him both Lord and Christ, this Jesus whom you crucified.” (Acts 2:36 ESV)
Peter’s explanation of the miracles of Pentecost, particularly the speaking in tongues, gave him an opportunity to preach the gospel. This short sermon contains the basic truths of Jesus ministry, death, and resurrection. These truths are enhanced by an appeal to the witness of the Old Testament Scriptures, as well as the eyewitness testimony of the apostles and the testimony of the people who were there listening.
The important truth that Peter wanted to convey to those listeners was that now is the day of salvation, now is man made right with God. This is possible only by the death and resurrection of Jesus, the very man that the Jews condemned and rejected several weeks earlier. Peter also let them know that Jesus was no ordinary man, something which was attested to by His rising from the dead. Jesus is the promised Messiah but He is also Almighty God Himself. Thus what He says and commands us to do must be heeded obeyed for He is the one to whom all humans are accountable. To ignore Him and His word is to invite judgment and condemnation.
Therefore the Lord Jesus has called everyone who has faith in Jesus to be His witnesses to the rest of the world. We must warn them of the consequences of their sins and their rejection of faith in Jesus. Like Peter we are called to tell them they need acknowledge their sins, repent, and be baptized. Then they would receive forgiveness, enter into the new life in the Kingdom of God and be filled by the promised Holy Spirit. In Jesus alone do we find the only cure for man’s ills and all the troubles which assail our world today.