From the proposition thus expressed in affirmative and negative form, John proceeds to draw the inference: "But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him." The commands of Christ are here referred back to his word, his doctrine in general. For John is not here speaking of single isolated moral precepts, but of the word revealed through Christ, embracing faith and life in their whole extent; his commands being, as we have already remarked, only single features in which his life-transforming word is developed. Of one who thus observes this word and applies it in practice, the Apostle says that in him the love of God has reached its completion; that is, love to God, such as it must be to correspond to the idea of love, is existing in him. It forms the opposite of such a love to God as cannot be called genuine love; a love to God professed in words alone, giving no evidence of itself in practice, and contradicted by the course of life. Here also it is obvious, that although John only presents these opposites in their generic form, yet we are necessarily led to the idea of gradational differences in the actual life. Whilst genuine love can manifest itself only by obedience to the word of Christ, yet there being differences as to the degree in which this love has penetrated the whole life with its vitalizing influence, and eradicated whatever is selfish; there will be corresponding differences as to the manifestation of its power, in obedience to the word of Christ, in the fulfilment of his commands. We must constantly bear in mind, that it is not love to God in a merely general and indeterminate sense which is here presented, but love to God in the christian sense, with all which is necessarily presupposed in it as such. It is love to God in connection with the knowledge of Christ, and having its source therein; love to God as the Father, enkindled by the revelation of the redeeming love of God in Christ. John knows indeed of no other love to God. He beholds in man a being estranged from God; over whom impends the divine wrath, till succored by the redeeming love of God in the sending and sacrifice of his Son. It is through this alone that man becomes capable of loving God as a Father, and is constrained so to love Him. This love is now the new principle of life; is that which, if genuine, must of itself impel him who feels it to fulfil the word of Christ, to obey his commands. Thus with John, true knowledge of Christ and true love to God are in every respect coincident; and the actual life must furnish the test of both.

Hence he says: "Hereby we know that we are in him." Here the Apostle brings to view a state of being, which has its foundation in Christ; just as Christ is by Paul represented, as himself the foundation on which the whole structure of the Christian life is built, whereon it rests. Thus each believer has his life in Christ; its root is spiritual fellowship with him. To be a christian and to be in Christ, to be in fellowship with him and to live, are in the view of John one and the same thing. Christ himself is here the vital principle from which all proceeds. Out of him unfolds itself the entire new life. To know Christ, to love God as self-revealed in Christ, to be in Christ, these are all indissolubly connected, are one and the same; one cannot be conceived separate from another. And thus also, as we see, obedience to the word, to the commands of Christ, is the test whether one is truly in a state of fellowship with Christ.