The first challenge in this passage is to find a common thread linking the verses together. Two key terms are helpful, the first appearing in Jesus’ words in verse 40: “for whoever is not against us is for us” (NIV). What does “against” imply—strictly direct opposition? If we locate “against” in the broader context of Scripture, we see that “against” also includes indifference or being lukewarm. To ignore Jesus would also imply “against” by way of not being for Him. There is no neutral ground—you are either for or against Jesus and His own.
The other important concept that arises in relation to “against or for” is “hinder.” We are not to deter anyone who shows any inclination toward the Christ. “Do not hinder him,” Jesus said in responding to the question in verse 38 (it seems to be more of a “was that OK?” than a statement about any feelings of superiority to the exorcist). Jesus then proceeded from there to give further examples of those “not against” who should not be “hindered.” The warning against hindering the exorcist moves on to a warning against hindering those who offer a cup of cold water, hindering children who believe, to members of our own body that would hinder our faith walk.
With these concepts in mind, let us now return to the first segment (38-41): John tells the Master that he tried to stop someone from using Jesus’ name in an exorcism, and he appears to be wondering if he did the right thing. Isn’t it interesting that back in verse 18, John included an account of the disciples failing in their attempt to exorcise a demon? When the father of the demonized boy pleaded with Jesus for help, Jesus answered, “Everything is possible for one who believes” (v. 23, NIV, emphasis added). Now, what if we connect this “who believes” to the successful exorcism referenced by verse 38? Jesus obviously interpreted that exorcism as an expression of the man’s favor toward Him: “for whoever is not against us is for us.” Do not hinder that. Jesus then gave another example in the possible offering of something even so small as a cup of cold water to the disciples, because they belong to the Christ. Again, recognize the favor of the gift giver’s heart toward Jesus—as an expression of love that is ultimately directed to Jesus via the act of giving hospitality to His disciples. Jesus did not speak of this as merely an expression of humanitarianism, but as an act of honoring Christ through His disciples. Do not hinder or refuse that. In the example of causing little ones to “stumble” (skandalizo), the Greek root is skandalon, referencing the piece of wood that kept open a trap for animals or the movable part of a trap on which the bait was laid (http://biblehub.com/greek/4625.htm, accessed 9/2/2015). R.C.H. Lenski similarly pointed out that this “stumbling” is not simply a fall from which one recovers, but the destruction of the soul, “as an animal is caught by touching the bait affixed to the crooked stick in a dead-fall trap. The sense is: whoever destroys a child or a childlike believer spiritually incurs the greatest wrath of Jesus” (The Interpretation of St. Mark’s Gospel, Augsburg Publishing House, 1946, 401). Do not hinder them, for “they are precious in His sight,” as goes the song. Jesus warned even against self-entrapment caused by our hand, foot or eye. If that should happen, “cut it off…pluck it out…” Of course, Jesus is not advocating that we literally dismember ourselves, but teaches that the eternal salvation of our soul is far more important than preserving a limb. The serious consequence of sin’s entrapment is clear from verses 47-49: the fire and the worm are both “unquenchable” and eternal, like nothing on earth. It is as though Jesus said, “It’s horrible—don’t go there!” Regarding our eternal salvation, there is no sacrifice too great to obtain it.
So then, if Jesus is not advocating amputation, what is his alternative? He did not elaborate much here, but we know more from other words of Scripture. The prophet Ezekiel, for example, expressed God’s plan for us this way: “I will give you a new heart and put a new spirit in you; I will remove from you your heart of stone and give you a heart of flesh” (Ezek. 36:26 NIV). Jesus appealed to this new heart when he concluded, “Have salt among yourselves, and be at peace with each other” (v. 50, NIV). God’s missionary people are “for” Christ, the world sees this in our bond of peace and unity in Christ. Jesus prayed for this in His High Priestly prayer in John 17: “I do not ask on behalf of these alone, but for those also who believe in Me through their word; that they may all be one; even as You, Father, are in Me and I in You, that they also may be in Us, so that the world may believe that You sent Me” (Jn. 17:20-21, NIV, emphasis added). Do not hinder another, but encourage their faith, “for whoever is not against us is for us” (v. 40, NIV). This is Christ’s calling for His people, the Church.