Jesus, having received John’s request for a rebuke, corrects John rather than crushing him. He does this by explaining to John that the concern is ultimately for the cause of Christ – and not for the cause of the 12. Again, and in another manner, Jesus teaches his disciples that discipleship concerns following Jesus – not in following any banner or cause or man. Salvation is ultimately a matter of personal love and obedience and discipleship, in a word, faith in Jesus as the one sent by the Father to redeem the world.
John’s concern was with their visible union, not the profound faith of a disciple upon Jesus:
In refusing to recognize the exorcist fellow-worker, however humble, as a brother, the disciples proceeded on very narrow and precarious grounds. The test they applied was purely external. What sort of man the person interdicted might be they did not inquire; it was enough that he was not of their company: as if all inside that charmed circle–Judas, for example–were good; and all outside, not excepting a Nicodemus, utterly Christless! Two good things, on their own showing, could be said of him whom they silenced: he was well occupied, and he seemed to have a most devout regard for Jesus; for he cast out devils, and he did it in Jesus’ name. These were not indeed decisive marks of discipleship, for it was possible that a man might practice exorcism for gain, and use the name of Christ because it had been proved to be a good name to conjure by; but they ought to have been regarded as at least presumptive evidence in favor of one in whose conduct they appeared. Judging by the facts, it was probable that the silenced exorcist was an honest and sincere man, whose heart had been impressed by the ministry of Jesus and His disciples, and who desired to imitate their zeal in doing good. It was even possible that he was more than this–a man possessing higher spiritual endowment than his censors, some provincial prophet as yet unknown to fame. How preposterous, in view of such a possibility, that narrow outward test, “Not with us “!
To illustrate this point, Bruce tells the story of on Sir Matthew Hale of the time of Richard Baxter. All accounted Hale a good and moral man, but there were those who questioned his salvation because he did not attend their private prayer meeting! They defined the elect not by their devotion to Jesus, but their membership in their meeting.
Such drawing a line between those inside and those may – and often times does – result from pride developed to a critical spirit. It may stem from jealousy of power and desire for the exaltation of self:
In silencing the exorcist the twelve were probably actuated by a mixture of motives–partly by jealousy, and partly by conscientious scruples. They disliked, we imagine, the idea of any one using Christ’s name but themselves, desiring a monopoly of the power conferred by that name to cast out evil spirits; and they probably thought it unlikely, if not impossible, that any one who kept aloof from them could be sincerely devoted to their Master.
In so far as the disciples acted under the influence of jealousy, their conduct towards the exorcist was morally of a piece with their recent dispute who should be the greatest.
Yet, not all such criticism of those outside in the favor of those “inside” stems from pride. If it has come from pride, then the response must be admonition and instruction which leads to repentance. In fact, such sharp tongued and narrowed soul people (who often line the internet) can easily become the factious man of Titus 3:9-11
9 But avoid foolish controversies, genealogies, dissensions, and quarrels about the law, for they are unprofitable and worthless. 10 As for a person who stirs up division, after warning him once and then twice, have nothing more to do with him, 11 knowing that such a person is warped and sinful; he is self-condemned. Titus 3:9–11 (ESV)