Hi, the information to what the seven thunders said in the book of Revelation is in the Bible but at the point of Revelation chapter 10 the order was for the words spoken to be kept secret. Why is this important to us? Because the human that can reveal the words spoken can verify themselves as God as in Revelation 21:3 and Revelation 12:1–2. What information in the Bible can help us understand God’s plan? At Daniel 12:4 it says “But you, Daniel, keep this message a secret. You must close the book and keep this secret until the time of the end. Many people will go here and there looking for true knowledge, and the true knowledge will increase.”
During the time of the end or the final days The Second Coming of Christ will reveal the true God like a secret kept silent until the right time should come. This is a special time because so much doubt and false teaching was spread over thousands of years, but people are still searching for the truth. God allowed this to happen so that at the Second Coming of Christ it will be as an exposing of truth to resolve all these religious issues, Isaiah 2:2-4. These are the words spoken with voices that sounded like 7 thunders:
Easy-to-Read Version (ERV)
Grace and peace to you from the one who is, who always was, and who is coming; and from the seven spirits before his throne; 5 and from Jesus Christ. Jesus is the faithful witness. He is first among all who will be raised from death. He is the ruler of the kings of the earth.