You know the millstone thing is parable right? Jesus told us ALL these things are done in parable.
"If anyone causes one of these little ones—those who believe in me—to stumble, it would be better for them to have a large millstone hung around their neck and to be drowned in the depths of the sea."
In Genesis, the gathered waters He called seas. In Revelation, we're told the waters stand for people.
Jesus told us we're one in Him. If someone makes a child lose faith in Him, and the child is One with Him so therefor faith in themselves, it would be better for them if they were to have a large millstone hung around their neck and to be drowned in the depths of the sea.
"As he taught, Jesus said, “Watch out for the teachers of the law. They like to walk around in flowing robes and be greeted with respect in the marketplaces, and have the most important seats in the synagogues and the places of honor at banquets. They devour widows’ houses and for a show make lengthy prayers. These men will be punished most severely.”