The seven thunders appear in Revelation 10:1–7. In his apocalyptic vision, the apostle John saw a mighty angel striding the sea and the land with a scroll in his hand. The angel gave a shout like the roar of a lion, and then the voices of the seven thunders spoke. Just as John was about to write down what they said, a voice from heaven told him the following.. “And when the seven thunders had uttered their voices, I was about to write: and I heard a voice from heaven saying unto me, Seal up those things which the seven thunders uttered, and write them not.” Revelation 10:4
The incident of the seven thunderous voices occurs in the interlude between the sixth and seventh trumpets. The seven thunders are not just the usual sound of thunder but are thunder-like voices communicating a message. The Greek word translated “thunder” means “to roar.” Thunder is often a mark of judgment in Scripture as in 1 Samuel 2:10, 2 Samuel 22:14, and several more places in Revelation (8:5, 11:19, 16:18), so these seven powerful voices are crying out for God’s judgment upon the sinful earth. The thunder represents the voice of God.
“The Lord also thundered in the heavens, and the Highest gave his voice; hail stones and coals of fire.” Psalm 18:13
“And out of the throne proceeded lightnings and thunderings and voices: and there were seven lamps of fire burning before the throne, which are the seven Spirits of God.”Revelation 4:5
The voice of God is depicted as thunderous rumblings that display the power, majesty and glory of the Lord. In this verse, John saw a preview of the divine wrath to be poured out on the earth as described in full in Revelation chapters 16—19.
Just as John was about to write the words of the seven thunders, a voice from heaven commands him to seal up what was revealed by them. The same throne that issues forth lightning and thunder issues a command to keep secret what the voices have revealed. The reason for the sealing is not given, but it could be that the judgment was simply too terrifying to be recorded. The content of the message is never revealed in Scripture, so we can’t speculate on its specifics. The seven thunders are the only words in Revelation that are sealed.