[A]nd then he cried out in a loud voice as a lion roars. When he cried out, the seven thunders raised their voices, too,
(Revelation 10:3; all translations NAB, Rev. Ed. unless otherwise noted).
The seven thunders are closely associated with the lion’s roar of the angel—they could be interpreted as a sort of echo, as one commentator understands them, or as a kind of response to the cry of the angel. The thunder of heaven is almost entirely unique to Revelation—appearing in eight other chapters and almost nowhere else in the New Testament. It is sometimes associated with a specific being. Here is another example:
Then I watched while the Lamb broke open the first of the seven seals, and I heard one of the four living creatures cry out in a voice like thunder, “Come forward.” I looked, and there was a white horse, and its rider had a bow. He was given a crown, and he rode forth victorious to further his victories (Rev. 6:1).
We know from Ezekiel that the living creatures are also the cherubim, a type of angel associated knowledge of divine things and intimate nearness to God. So it is fitting that the living creatures—who are angels—speak in thunder just as the giant angel of Revelation 10.
But other times the thunder is not connected to a specific visible being and instead is a kind of omnipresent phenomenon associated with visions of heavenly worship and the throne of God:
Then God’s temple in heaven was opened, and the ark of his covenant could be seen in the temple. There were flashes of lightning, rumblings, and peals of thunder, an earthquake, and a violent hailstorm (Rev. 11:19).
The thunder has a specific meaning that draws upon the Old Testament. It often accompanies God’s judgment and punishment of His enemies, such as in 1 Samuel 7:10 when God “thundered loudly” against the Philistines, leading to their defeat by Israel. But it is also more generally associated with His glory and power, as in Psalm 29:
The voice of the Lord is over the waters;
the God of glory thunders,
the Lord, over the mighty waters.
The voice of the Lord is power;
the voice of the Lord is splendor.
The voice of the Lord cracks the cedars;
the Lord splinters the cedars of Lebanon,
Makes Lebanon leap like a calf,
and Sirion like a young bull.
The voice of the Lord strikes with fiery flame;
the voice of the Lord shakes the desert;
the Lord shakes the desert of Kadesh.
The voice of the Lord makes the deer dance
and strips the forests bare.
All in his Temple say, “Glory!” (Ps. 29:3-9).
Thunder then signifies God in all his majesty. It represents the manner in which God’s omnipotent and absolute holiness out to inspire awe and a kind of holy fear in us.
What is happening here is akin to how mystical theologians sometimes speak about the ‘appearance’ of God. His true brightness would overwhelm our eyes, blinding us. St. Gregory of Nyssa calls this the ‘dazzling darkness.’ This is why the angel, who some commentators see as Christ, has a face like the sun. So also with the voice of God: it is a deafening thunder.
The thunder thus represents God’s simultaneous presence to us and His incomprehensibility. As Job puts it,
Listen to his angry voice
and the rumble that comes forth from his mouth!
Everywhere under the heavens he sends it,
with his light, to the ends of the earth.
Again his voice roars,
his majestic voice thunders;
he does not restrain them when his voice is heard.
God thunders forth marvels with his voice;
he does great things beyond our knowing
(Job 37:2-5; notice how thunder is paired with light).
But the thunder of God is not meant to only inspire reverence among us. It is something to which we should feel drawn. We should not only bow before the thunder, but we should listen to it.
Now, how can we do this?
The same way we grow spiritually in order that we might one day ‘see’ God, what is traditionally called the beatific vision. Matthew 5:8 tells us we do this by becoming ‘pure in heart.’
We also do it by preparing our vision, in a way: by contemplating Christ on the cross, we are drawn up to the vision of the invisible God. In the same way, by listening to the words of Christ in the gospels we are prepared to hear God in all His thunderous glory. As Christ says in John 10, speaking of Himself as the shepherd,
When he has driven out all his own, he walks ahead of them, and the sheep follow him, because they recognize his voice (John 10:4).
We know that is possible to hear the divine voice because John heard it and so did Job, even as he conceded God was beyond his comprehension (see Rev. 6:1, Rev. 10:4, and Job 37:6). And two chapters later, in John 12, a voice speaks from heaven that sounds like thunder, but some in the crowd around Jesus are able to discern its message:
“I am troubled now. Yet what should I say? ‘Father, save me from this hour’? But it was for this purpose that I came to this hour. Father, glorify your name.” Then a voice came from heaven, “I have glorified it and will glorify it again.” The crowd there heard it and said it was thunder; but others said, “An angel has spoken to him.” Jesus answered and said, “This voice did not come for my sake but for yours (John 12:27-30).
So let us meditate on Christ’s words in the gospels that we may learn to listen to the thunder.