Then there arose a reasoning among them, which of them should be greatest.  And Jesus, perceiving the thought of their heart, took a child, and set him by Him, and said unto them,
“Whosoever shall receive this child in My name receiveth Me: and whosoever shall receive Me receiveth Him that sent Me: for he that is least among you all, the same shall be great.”
Luke 9:46-48

There were some of the disciples who thought Jesus was going to set  up His kingdom on earth.  In verses preceding our text today, tells us that Jesus had told them once again that He was going to die at the hands of men.  They refused to hear it, not understanding what He was saying.  How could these men miss what Jesus told them several times?

They had preconceived ideas about the Messiah.  The death of Messiah was unthinkable to these men.  Because of the way they believed about Jesus, and thinking Jesus was there to set  up the Messianic kingdom, they were asking where they were going to sit in that kingdom, seeking for greatness.

Jesus takes a young child and sets him by Himself, and explains who the greatest will be.  The child was young, and still trusting, and humble before  God and others  too.  He was not seeking for greatness.

Anyone desiring to be great will be last; and he that is last shall be first.  To be saved from our sins we must humble ourselves before  Christ seeking Him and a cleansed life.  Trust  in the Lord, believe Him.