Under the term spirit, the Apostle here comprehends two things outwardly alike, but differing in their inward and essential nature, -- viz. true and false inspiration, what originates in the suggestions of the divine spirit, as well as in those of the undivine. He who judged by no other test than appearance merely, must suppose he witnessed in all these outward manifestations the same power of inspiration, revealing itself in words of resistless fervor. And here a twofold error might be committed. Christians might either yield themselves credulously to all which claimed to be the revelation of a higher spirit, allowing themselves to be hurried away as the blind instruments of every influence; or, detecting the suggestions of the undivine spirit and seeking to avoid its delusions, might be thereby led to suspicion and distrust of all such manifestations, of every kind of inspiration. As there was a false confidence of unquestioning credulity, so might there arise also a morbid scepticism of mistrust, whereby the influences of the Holy Spirit might be obstructed in the church, and the kindling flame of inspiration be at once extinguished. Against both these errors, Paul thought it necessary to warn the church at Thessalonica. (1 Thess. v.19, ff.)
The same danger which then threatened the christian life, must, by virtue of the uniform law in christian development, be constantly repeated; and the healthful christian spirit, alike far from blind credulity and from suspicious and unloving distrust, must trace out for itself the right way between these two extremes. This finds a special application in times which resemble the apostolic age; viz. when Christianity, -- though not indeed making its first entrance into the world, yet rising anew from victorious conflict with the hostile forces of superstition or of scepticism, -- begins to work with a new power; when a new outpouring of the Holy Spirit is preparing the way for itself, and gives tokens of its coming; in all times of special religious awakening, or of a spiritual excitement which affects the religious sphere. In such times, there will always be found some who are caught by everything unusual; who give ear too readily to everything which assumes the language of religious zeal; who behold the Divine in everything which proceeds from a state of peculiar mental excitement, and claims to be the work of the Holy Spirit. Others, on the contrary, detecting this infusion of foreign elements, suffer themselves to be thereby made distrustful towards all religious awakening. Instead of trying the spirits, they class them all together and reject all; and thus, as far as in them lies, they extinguish also the divine flame, and prevent the growth of that new religious life from which a new creation was to be developed. The warning of the Apostle not to believe every spirit, his requirement to test the spirits, includes a caution against both these errors. In his caution not to believe every spirit, it is implied that we are not to reject all which claims to be the voice of the Holy Spirit; but should feel a confidence that here is in reality something divine. Hence he requires us to try the spirits, as a means of learning to distinguish the true from the false, what proceeds from a divine spirit and what from an undivine.
But though the Apostle has in view both errors, it is here his special object to warn against the delusions of false prophets, and to furnish a test by which these should be recognized. What he here says tallies with his previous warning against the seductions of false teachers. So also the mark, for distinguishing between the true and the false, is in both cases the same. As we have before seen, the preaching of Jesus, as the divine-human Saviour and theocratic King, is the centre of all. To acknowledge Jesus as the Christ, this in John's view is synonymous with acknowledging him as He who appeared in the flesh, -- the Son of God manifested in the flesh, -- the eternal Word in his humanization, -- the eternal divine life-fountain letting itself down into human nature, and revealing itself in visible human form, -- the truly divine and human, in harmonious union. In this is involved the rejection of that spectral sublimation of the Idea of Christ, already mentioned; of all which tended to separate the only-begotten Son of God from Him who has appeared in the flesh, -- to obscure the unity between the divine and its manifestation in the flesh. That one divine fact, John makes the centre of all. It was, as we before remarked, the grand point of controversy in that age, as it is the one around which gather all the vital questions of the present time. Here again there is no other test of true faith, no other law for christian union, than steadfast adherence to that one fundamental fact of the appearing of the Divine-human Redeemer. In all which proceeds from this belief, the influences of the divine Spirit should be acknowledged. Hence it follows, that provided faith in this one fundamental fact be the soul of the christian life, no minor differences of creed should be allowed to disturb christian unity; that mistakes and alloys of christian truth, which trench not on this one fundamental fact, should not hinder us from recognizing the divine stamp in him whose faith and profession have their root therein, -- that the bonds of christian fellowship should not thereby be sundered or loosened. Steadfast adherence to this one foundation is the mark of being from God, of the spirit derived from God. Of course, he who adheres to it is in fellowship with God, is a partaker of the divine life, is animated and led by the Spirit of God; and from it will securely proceed the purification of the whole life, both in knowledge and practice. Thus the Saviour, comparing himself to the vine and believers to its branches (John xv. i ff.), says that these branches are to be more and more cleansed in order that they may bring forth the more fruit. That is: believers, abiding in fellowship with him, will thereby continue to partake of the divine life diffused from him through all his members; and being thus, in the divinely ordained and directed development of that life, more and more purified from the foreign and undivine which still obstructs it, will bring forth more and more of its fruits in their whole life and conduct. This then is applicable to all such, as through adherence to that one radical fact are branches of the true vine; and in them will be experienced, in their faith, views, and practice, the quickening energy of that divine life, which spreads from the vine-stock through all the branches, cleansing away all that is foreign.
But while John presents both the affirmative and negative aspect of this characteristic mark, it is here his special object to enforce the negative; to warn against all manifestations of that spirit which does not acknowledge this radical fact, but either denies or mutilates it. Whoever so taught was to be at once rejected. No other mark for the designation of the undivine, the antichristian, the false, should be needed for the believer. In all such manifestations the Apostle recognizes the spirit of Antichrist, whose culminating point, self-deification, was to precede the triumphant revelation of Christ in the last time. In all which denies or mutilates this one ground-fact, he bids us discern the tokens of that approaching Antichrist, whose spirit is thus shown to be already in the world and preparing for his full manifestation. He calls upon believers to watch for, and at once and totally to reject, all such manifestations; lest, being gradually drawn aside from the one foundation, and yielding themselves to the delusions of that antichristian spirit, they might at length come wholly under its dominion.