The apostle John recognizes that judgment is being made against Babylon when he sees the strong angel toss
a stone like a great millstone (Rev 18:21).
Two heavy circular millstones are used for grinding grain: one lying flat as a base and the
other standing up rolling on an axel atop of the flat circular base.
Then a strong angel took up a stone like a great millstone and threw it into the
sea, saying, "So will Babylon, the great city, be thrown down with violence, and will not be found any
longer." (Rev 18:21)
When speaking of deceit and causing others to go astray, Jesus mentions the use of a millstone
in the figurative sense to warn against and emphasize the seriousness of the offense. And this is what Babylon was
precisely guilty of.
Whoever causes one of these little ones who believe to stumble, it would be better for
him if, with a heavy millstone hung around his neck, he had been cast into the sea.