The sermon recounts the momentous events of Pentecost, emphasizing the outpouring of the Holy Spirit upon believers and the subsequent transformation of the early church. It details the disciples' gathering, the miraculous manifestation of speaking clearly and distinctly in foreign languages, and Peter's compelling explanation rooted in Old Testament prophecy, particularly Psalm 16. The narrative highlights the conversion of approximately 3,000 individuals, their communal lifestyle marked by shared possessions and unwavering fellowship, and the ongoing addition of new believers, all demonstrating a unified devotion to Christ and a profound sense of God's favor.