How do we know the significance of preaching from Acts 2?

The preaching of Peter in Acts 2 serves as a critical focal point for understanding the significance of gospel preaching in the New Testament. Peter's sermon, which references the fulfillment of prophecy from Joel, emphasizes that the preaching of the gospel is central to the Church's mission. The listeners' responses—being amazed, mocking, or converting—illustrate the different reactions people have to the gospel. This passage reinforces that true preaching must be Spirit-filled to effectively communicate God’s truth and bring about conviction and conversion.