What does Revelation 19:9 mean?
John has heard the praises of a vast multitude singing to God (Revelation 19:6). The angel who has been guiding John through this part of his vision (Revelation 17:1–3) now gives him a specific task: writing the message of this verse.This statement distinguishes between the bride and other believers. The bride, by definition, is not invited to her own reception. Those who are "invited" are the friends of the bridegroom. John the Baptist, for example, referred to himself as the friend of the bridegroom. He said, "The one who has the bride is the bridegroom. The friend of the bridegroom, who stands and hears him, rejoices greatly at the bridegroom's voice. Therefore this joy of mine is now complete" (John 3:29).
So, John the Baptist will surely be invited to the marriage supper of the Lamb. Abraham, Isaac, and Jacob will be invited too (Matthew 8:11). A common interpretation of this passage is that likely all the Old Testament believers and the tribulation believers will also be included as invited guests. The angel who spoke to the apostle John emphasized the fact that what he said about the marriage supper of the Lamb were the true words of God.