Rev. 6:12-17 (ESV)
When he opened the sixth seal, I looked, and behold, there was a great earthquake, and the sun became black as sackcloth, the full moon became like blood,  and the stars of the sky fell to the earth as the fig tree sheds its winter fruit when shaken by a gale.  The sky vanished like a scroll that is being rolled up, and every mountain and island was removed from its place.  Then the kings of the earth and the great ones and the generals and the rich and the powerful, and everyone, slave and free, hid themselves in the caves and among the rocks of the mountains,  calling to the mountains and rocks, "Fall on us and hide us from the face of him who is seated on the throne, and from the wrath of the Lamb,  for the great day of their wrath has come, and who can stand?"
Judgment day is depicted in horrible glory. The end of the world, what else could it be? The sixth seal revisits common themes of the Old Testament in depicting this day, and these times. The sun turns black. The moon turns blood red. They sky rolls up like a scroll. It is a fearful depiction. The people run for shelter to mountains that disappear. Mountains, those ever faithful fortresses that make it hard for armies to operate, a natural safe haven, they fail. They disappear. The people pray for them to fall upon them. “The great day of wrath has come, and who can stand?”
No one can stand, not on their own feet. Only those who stand in Christ can stand. He alone is righteous. He alone escapes judgment. Him and his body, the church. Everyone else no matter position flees for the hills, and the hills betray them, give them up.
In the end all will bow. In the end all will recognize. But for many the end will just be too late.