There are words we sometimes try to use to describe them, but they're pale, pathetic shadows.
Openheimer was right.
Azathoth, one of the three Lovecraftian Elder Gods, is described as being the basis for nuclear explosions. They're a small fraction of his being, teleported onto earth, in a wave of nuclear insanity. Is it any surprise that people would think this, after seeing the way a single bomb could cause so much destruction?
Edit: That might not be canon, and instead the product of my own wacky mind... But meh.