A.T. Robertson Commentary Luke 18:17

"Verily I say unto you, Whosoever shall not receive the kingdom of God as a little child, he shall in no wise enter therein." — Luke 18:17 (ASV)

As a little child (ως παιδιον). Jesus makes the child the model for those who seek entrance into the kingdom of God, not the adult the model for the child. He does not say that the child is already in the kingdom without coming to him. Jesus has made the child's world by understanding the child and opening the door for him.