Pastor Mark spoke about the uniqueness and, honestly, the difficulty of the Kingdom of God. Where it is that one is great when one is last. Where it is that one is great when one is the servant of all. The disciples had a difficult time grasping this because it is simply difficult to grasp. So Jesus brings a child and puts the child among them. Understanding and welcoming children is crucial to understanding and welcoming the Kingdom. 

Scripture:

Psalm 1

James 3:13-4:7

Mark 9:30-37