Context and Background:
Peter's Sermon, delivered on the day of Pentecost, is a pivotal moment in the New Testament, marking the birth of the Christian Church. This event is recorded in the Book of Acts, specifically in Acts 2:14-41. The sermon follows the miraculous outpouring of the Holy Spirit upon the apostles, enabling them to speak in various tongues, which astonished the diverse crowd gathered in Jerusalem for the feast of Pentecost.

Content of the Sermon:
Peter, standing with the eleven apostles, addresses the crowd to clarify the events they are witnessing. He begins by refuting the accusation that the apostles are drunk, explaining that it is only the third hour of the day (Acts 2:15). Instead, Peter interprets the phenomenon as the fulfillment of the prophecy from the Book of Joel, stating, "In the last days, God says, I will pour out My Spirit on all people" (Acts 2:17).

Peter's sermon is structured around several key themes:

1. Fulfillment of Prophecy:
Peter emphasizes that the events of Pentecost fulfill Old Testament prophecies. He cites Joel 2:28-32 to demonstrate that the outpouring of the Holy Spirit was foretold by the prophets, indicating the arrival of the "last days."

2. The Life, Death, and Resurrection of Jesus Christ:
Central to Peter's message is the proclamation of Jesus as the Messiah. He recounts Jesus' ministry, His crucifixion at the hands of lawless men, and His resurrection by the power of God. Peter declares, "God has raised this Jesus to life, to which we are all witnesses" (Acts 2:32).

3. Exaltation of Jesus:
Peter asserts that Jesus has been exalted to the right hand of God and has received from the Father the promised Holy Spirit, which He has poured out upon the believers (Acts 2:33). He references Psalm 110:1 to affirm Jesus' lordship, stating, "The Lord said to my Lord: 'Sit at My right hand, until I make Your enemies a footstool for Your feet'" (Acts 2:34-35).

4. Call to Repentance and Baptism:
Concluding his sermon, Peter calls the crowd to repentance and baptism in the name of Jesus Christ for the forgiveness of sins, promising that they too will receive the gift of the Holy Spirit (Acts 2:38). He urges them to "Save yourselves from this corrupt generation" (Acts 2:40).

Impact and Response:
Peter's sermon results in a profound response from the audience. The listeners are "cut to the heart" and inquire what they should do (Acts 2:37). Approximately three thousand individuals accept his message, are baptized, and are added to the early church that day (Acts 2:41). This event signifies the beginning of the Christian mission and the expansion of the church, as the apostles continue to preach the gospel with boldness and perform signs and wonders.

Theological Significance:
Peter's Sermon is foundational for Christian theology, emphasizing the continuity between the Old Testament prophecies and the New Testament fulfillment in Christ. It underscores the centrality of Jesus' death and resurrection in God's redemptive plan and the necessity of repentance and faith for salvation. The sermon also highlights the role of the Holy Spirit in empowering believers and establishing the church as the community of God's people.