Jesus used a child to illustrate for his disciples how they should think and behave. We are not to be childish (like the disciples arguing over petty things) but childlike, with humble, sincere, and trusting hearts.
The disciples had become to preoccupied with the organization of Jesus’ earthly kingdom that they had lost sight of it’s divine purpose. Instead of seeking a place of service, they sought positions of esteem. It is easy to lose our eternal perspective and compete for promotions or status in the church.
Jesus warned the disciples about two ways to cause others to sin; tempting and neglecting or demeaning them. As leaders, we are to help young people and new believers avoid anything or anyone that could cause them to stumble in their faith and lead them to sin.
And Jesus says to remove stumbling blocks that cause us to sin. This does not mean to cut off a part of your body. For the church it means that any person, program, or teaching that threatens the spiritual growth of the body must be removed. For the individual it means any relationship, practice, or activity that leads to sin should be stopped. Jesus says it would be better to go to heaven with one hand than to hell with both. Sin, of course, affects more than our hands; it affects our minds and hearts.