Question: "What is the marriage supper of the Lamb?"
In his vision in Revelation 19:7-10, John saw and heard the heavenly multitudes praising God because the wedding feast of the Lamb—literally the "marriage supper"—was about to begin. The concept of the marriage supper is better understood in light of the wedding customs in the time of Christ.
These wedding customs had three major parts. First, a marriage contract was signed by the parents of the bride and the bridegroom, and the parents of the bride would pay a dowry to the bridegroom or his parents. This began what was called the betrothal period—what we would today call the engagement. This period was the one Joseph and Mary were in when she was found to be with child (Matthew 1:18; Luke 2:5).
The second step in the process usually occurred a year later, when the bridegroom, accompanied by his male friends, went to the house of the bride at midnight, creating a torchlight parade through the streets. The bride would know in advance this was going to take place, and so she would be ready with her maidens, and they would all join the parade and end up at the bridegroom's home. This custom is the basis of the parable of the ten virgins in Matthew 25:1-13. The third phase was the marriage supper itself, which might go on for days, as illustrated by the wedding at Cana in John 2:1-2.
What John’s vision in Revelation pictures is the wedding feast of the Lamb (Jesus Christ) and His bride (the Church) in its third phase. The implication is that the first two phases have already taken place. The first phase was completed on earth when each individual believer placed his or her faith in Christ as Savior. The dowry paid to the Bridegroom’s Parent (God the Father) would be the blood of Christ shed on the Bride’s behalf. The Church on earth today, then, is “betrothed” to Christ and, like the wise virgins in the parable, all believers should be watching and waiting for the appearance of the Bridegroom (the Second Coming). The second phase symbolizes the Rapture of the Church, when Christ comes to claim His bride and take her to the Father's house. The marriage supper then follows as the third and final step.
Attending the wedding feast will be not only the Church as the bride of Christ, but others as well. The "others" include Old Testament saints who are going to be raised at the Second Coming, as well as the martyred dead of the Tribulation. As the angel told John to write, “Blessed are those who are invited to the marriage supper of the Lamb” (Revelation 19:9). The marriage supper of the Lamb is a glorious celebration of all who are in Christ!