I think this is similar to what the Apostle Paul saw and heard when he was caught up to the "Paradise"of the third heaven, but was not allowed to write down the details.
"I know a man in Christ, fourteen years ago—whether in the body, I do not know, or out of the body, I do not know; God knows—such a man, having been caught up to the third heaven. And I know such a man—whether in the body or out of the body, I do not know; God knows—that he was caught up into Paradise, and he HEARD inexpressible words, not being permitted to man to speak." (2 Corinthians 12:2-4)
So, what did they say? You'll have to ask John after when you see him. However, here are my thoughts:
I know from experience that we SEE lightening before we HEAR the thunder. And lightning is associated with the return of Jesus to earth.
“For just as the lightning comes from the east and flashes even to the west, so will the coming of the Son of Man be.” (Matthew 24:27)
Therefore it seems logical that the "peals of thunder" spoke of what follows the return of Jesus to earth. Chapters 1 through 20 deal with the seven years leading up to the return of Jesus to earth to reign for 1000 years. I think that in Chapters 21 and 22 John writes down what the thunders said to him in Chapter 10. It was the hope of a New Heaven and New Earth.
“And I saw a new heaven and a new earth for the former heaven and the former earth pass away…and I saw the holy city, new Jerusalem, descending out of heaven from God..God is with mankind...and He will be brushing away every tear from their eyes. And death will be no more, nor mourning, nor misery; they will be no more, for the former things have passed away" (Revelation 21:1-4)
In Chapters 8 and 9 six angels had SHOWN John details of what will happen during the years just before the return of Jesus. Then in Chapter 10 he HEARD the "seven peals of thunder" tell him what would happen after the destruction of this earth, but was not allowed to write down what they said until he had written down the consummation of the “the mystery of God”.
“…in the days of the voice of the seventh angel, when he is about to sound, then the mystery of God is finished as He preached to His servants the prophets.” (Revelation 10:7)
So, I think the thunders told John about the New Heaven and New Earth. I think he heard about the salvation of all humanity and their reconciliation to God later revealed to the Apostle Paul by the risen Jesus. The prophet Isaiah called it a time when humanity will “rejoice and be glad in His salvation”.
“And it will be said in THAT DAY, Behold, this is our God for whom we have waited that He might save us. This is the LORD for whom we have waited; Let us rejoice and be glad in His salvation." (Isaiah 25:9)
“For just as the lightning comes from the east and flashes even to the west, so will the coming of the Son of Man be.” (Matthew 24:27)
Therefore it seems logical that the "peals of thunder" spoke of what follows the return of Jesus to earth. Chapters 1 through 20 deal with the seven years leading up to the return of Jesus to earth to reign for 1000 years. I think that in Chapters 21 and 22 John writes down what the thunders said to him in Chapter 10. It was the hope of a New Heaven and New Earth.
“And I saw a new heaven and a new earth for the former heaven and the former earth pass away…and I saw the holy city, new Jerusalem, descending out of heaven from God..God is with mankind...and He will be brushing away every tear from their eyes. And death will be no more, nor mourning, nor misery; they will be no more, for the former things have passed away" (Revelation 21:1-4)
In Chapters 8 and 9 six angels had SHOWN John details of what will happen during the years just before the return of Jesus. Then in Chapter 10 he HEARD the "seven peals of thunder" tell him what would happen after the destruction of this earth, but was not allowed to write down what they said until he had written down the consummation of the “the mystery of God”.
“…in the days of the voice of the seventh angel, when he is about to sound, then the mystery of God is finished as He preached to His servants the prophets.” (Revelation 10:7)
So, I think the thunders told John about the New Heaven and New Earth. I think he heard about the salvation of all humanity and their reconciliation to God later revealed to the Apostle Paul by the risen Jesus. The prophet Isaiah called it a time when humanity will “rejoice and be glad in His salvation”.
“And it will be said in THAT DAY, Behold, this is our God for whom we have waited that He might save us. This is the LORD for whom we have waited; Let us rejoice and be glad in His salvation." (Isaiah 25:9)
The Apostle Paul tells us that the “gospel” given to him by the resurrected Jesus was the mystery of Christ - the secret that all humanity, not just the people of Israel, will be saved.
“When you read this, you can perceive my insight into the mystery of Christ, which was not made known to the sons of men in other generations as it has now been revealed to his holy apostles and prophets by the Spirit. This mystery is that the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the gospel.” (Ephesians 3:4-6)
Paul refers to this mystery as “my gospel", which had been “kept secret” in the past.
“Now to Him who is able to establish you according to MY GOSPEL and the preaching of Jesus Christ, according to the revelation of the mystery which has been kept secret for long ages past…” (Romans 16:25-27)
Paul, the Apostle to the Gentiles, elaborates on what he calls “my gospel” in his New Testament letters. Paul explains in his letters that the mystery/secret revealed to is the good news of the grace of God bringing salvation and reconciliation of ALL created beings both on earth and in heaven.
“When you read this, you can perceive my insight into the mystery of Christ, which was not made known to the sons of men in other generations as it has now been revealed to his holy apostles and prophets by the Spirit. This mystery is that the Gentiles are fellow heirs, members of the same body, and partakers of the promise in Christ Jesus through the gospel.” (Ephesians 3:4-6)
Paul refers to this mystery as “my gospel", which had been “kept secret” in the past.
“Now to Him who is able to establish you according to MY GOSPEL and the preaching of Jesus Christ, according to the revelation of the mystery which has been kept secret for long ages past…” (Romans 16:25-27)
Paul, the Apostle to the Gentiles, elaborates on what he calls “my gospel” in his New Testament letters. Paul explains in his letters that the mystery/secret revealed to is the good news of the grace of God bringing salvation and reconciliation of ALL created beings both on earth and in heaven.
“For the grace of God has appeared bringing salvation to all people…God was in Christ, reconciling the world to Himself not counting their trespasses against them...and through Him to reconcile to Himself all things, whether things on earth or things in heaven, by making peace through the blood of His cross…" (Titus 2:11; 2 Corinthians 5:19; Colossians 1:19-20)
"Once you were alienated from God and were hostile in your minds because of your evil deeds. But now He has reconciled you by Christ’s physical body through death to present you holy, unblemished, and blameless in His presence." (Colossians 1:21-22)
"…the creation itself will be set free from its bondage to decay and brought into the glorious freedom of the children of God…in this hope we are saved; but hope that is seen is no hope at all. Who hopes for what he can already see? But if we hope for what we do not yet see, we wait for it patiently.” (Romans 8:19-25)
Again - "Creation itself will be set free" and "in this we hope" - Yes I do!
To me, the words of the "peals of thunder" is the really good news we HEAR about now, but will SEE in the future when God creats the New Heaven and New Earth. For now I just have faith in that future.
"Once you were alienated from God and were hostile in your minds because of your evil deeds. But now He has reconciled you by Christ’s physical body through death to present you holy, unblemished, and blameless in His presence." (Colossians 1:21-22)
"…the creation itself will be set free from its bondage to decay and brought into the glorious freedom of the children of God…in this hope we are saved; but hope that is seen is no hope at all. Who hopes for what he can already see? But if we hope for what we do not yet see, we wait for it patiently.” (Romans 8:19-25)
Again - "Creation itself will be set free" and "in this we hope" - Yes I do!
To me, the words of the "peals of thunder" is the really good news we HEAR about now, but will SEE in the future when God creats the New Heaven and New Earth. For now I just have faith in that future.
"Now faith is the assurance of things hoped for, the conviction of things not being seen." (Hebrews 11:1)