At that time the disciples came to Jesus and asked, “Who, then, is the greatest in the kingdom of heaven?”
He called a little child to him and placed the child among them. And He said: “Truly I tell you, unless you change and become like little children, you will never enter the kingdom of heaven. Therefore, whoever humbles himself like this child is the greatest in the kingdom of heaven. And whoever welcomes one such child in my name welcomes me.
“But if anyone causes one of these little ones who believe in me to sin, it would be better for him to have a large millstone hung around his neck and to be drowned in the depths of the sea. Woe to the world because of the things that cause people to sin!"
Matthew 18:1-7 (NIV)