Matthew 18:3-6

and said, “I assure you and most solemnly say to you, unless you repent [that is, change your inner self—your old way of thinking, live changed lives] and become like children [trusting, humble, and forgiving], you will never enter the kingdom of heaven. Therefore, whoever humbles himself like this child is greatest in the kingdom of heaven. Whoever receives and welcomes one child like this in My name receives Me; but whoever causes one of these little ones who believe in Me to stumble and sin [by leading him away from My teaching], it would be better for him to have a heavy millstone [as large as one turned by a donkey] hung around his neck and to be drowned in the depth of the sea. [Mark 9:42; Luke 17:2]