In Mark9:30-37 the disciples continue to be confused with Jesus’ message partly because their burning question was not “How can I live my life as Jesus?”, but rather, “How can I be seen as the greatest?”
Their self-centered thoughts were barriers to their understanding of what Jesus was telling them. In addition, their “arrogance,” reminiscent of Adam and Eve, breached the lines of communication with Jesus and their relationship with Him. They were unsuccessful in their attempt to heal the child because they were more intent on impressing the crowd; competing with each other and vying for Jesus approval rather than serving as instruments of God’s Peace.
In citing the child, Jesus is telling us that we have to welcome those “non-persons” who occupy the lowest rung of society’s ladder: "whoever welcomes one such child in my name welcomes me, and whoever welcomes me welcomes not me but the one who sent me."
Once again Jesus is challenging us to reverse long-standing, ingrained, human habits and to set aside our common human understanding of how to win fame and glory, and instead learn from Jesus, God's way.