John says to Jesus, “Teacher, we saw a man driving out demons in Your Name and we told him to stop, because he was not one of us.” (Mark 9:38, NIV) Jesus tells John not to stop the man. Jesus says, “No one who does a miracle in My Name can in the next moment say anything bad about Me, for whoever is not against us is for us.” (Mark 9:39-40)
Notice the man has been driving out demons in Jesus’ Name — not one demon, but many demons. He’s performed real miracles in the Name of the Lord, not once but many times. Yet, he does not belong to Christ, at least not according to the disciple, John.
Jesus says good performance doesn’t come from a man who sets himself against Him. If he is not against us, says Jesus, then he is for us.
“Whoever welcomes Me,” says Jesus, “does not welcome Me but the One who sent Me.” (Mark 9:37)