Mk 9:38-43, 45, 47-48
At that time, John said to Jesus,
"Teacher, we saw someone driving out demons in your name,
and we tried to prevent him because he does not follow us."
Jesus replied, "Do not prevent him.
There is no one who performs a mighty deed in my name
who can at the same time speak ill of me.
For whoever is not against us is for us.
Anyone who gives you a cup of water to drink
because you belong to Christ,
amen, I say to you, will surely not lose his reward.
"Whoever causes one of these little ones who believe in me to sin,
it would be better for him if a great millstone
were put around his neck
and he were thrown into the sea.
If your hand causes you to sin, cut it off.
It is better for you to enter into life maimed
than with two hands to go into Gehenna,
into the unquenchable fire.
And if your foot causes you to sin, cut if off.
It is better for you to enter into life crippled
than with two feet to be thrown into Gehenna.
And if your eye causes you to sin, pluck it out.
Better for you to enter into the kingdom of God with one eye
than with two eyes to be thrown into Gehenna,
where 'their worm does not die, and the fire is not quenched.'"
Jesus uses exaggerated notions and actions to make his disciples face the gravity of what they have done. By rebuking the unknown man who offered healing and exorcism in Jesus' name, the disciples had stopped up a tributary of divine compassion from flowing to those in need. In response, Jesus offers his disciples some of his harshest, most demanding judgments on what believers should do in order to avoid committing such sins.
The Jesus of love and mercy now uses images of force and fury to illustrate how deep his emotions run on this subject. Those who willfully erect "stumbling blocks," whose actions hinder the progress of "little ones," are declared better off at the bottom of the sea. So great is Jesus' love for these "little ones."