Peter through this sermon or preaching, will explain to the audience (many Diaspora Jews who had come for the special celebration, some to stay permanently in Jerusalem, some temporary) what is happening. God is doing this for a purpose. He will explain that this is a new beginning for Israel. From now on, the Holy Spirit will permanently reside within God’s people. This is possible because the Lord Jesus Christ died and rose from the dead, and this is why “God has made him Lord and Christ.” They must believe in Him as the Messiah and repent of their sins. In this way they will be part of this prophecy and be part of the assembly or Church that begins here and will bear witness to the world.