Mark 10:15

“Truly I say to you, whoever will not receive the Kingly Rule of God as a little child, he shall not under any circumstances enter into it.”

The real problem for men when they sought to come under the Kingly Rule of God was that they were not like children. They were not receptive, open, responsive, simple, believing. They were prejudiced, self-opinionated, proud, and unwilling to believe unless it fitted in with their ideas. Thus until they could put such things aside and become childlike in their openness and response, until they could come like children with nothing but their openness and need (compare Luke 18:13), they could not and would not receive the Kingly Rule of God.