Having previously spoken of obedience to commands in general, the Apostle now resolves the whole into obedience to that one command in which all is contained: "And this is his commandment; that we should believe on the name of his Son Jesus Christ, and love one another, as he gave us commandment."

The law of the Old Covenant began by instituting commands for the conduct. But the power so to conduct was wanting; and this no law could impart to man. Hence the Law could serve no other purpose than to bring man to the consciousness of his moral inability, of his discord with God and with his own better nature, to the consciousness of spiritual death. Here now, on the contrary, all commands are resolved into one; and this has reference not to a DOING, but to a BELIEVING, -- the command of the Father that we should believe on the name of his Son Jesus Christ; should believe on him in the relation in which he is presented to man by God as his only-begotten Son, as He through whom alone we can come to the Father, the Redeemer from sin, the Lord to whom henceforth should belong the whole life. So Christ, when asked by the Jews what they should do that they might work the works of God, gave no other answer than this: That they should believe on him whom God had sent; implying that in this was contained the source and sum of all. (John vi.29.)

Belief, however, is a matter of conviction. How then can it be commanded a man, to make this or that an object of conviction to himself? This stands not within his own power, it depends not on his own will; for conviction is an involuntary thing. God would have instituted no such requirement, had not He, who is to be the object of belief, so corresponded to the requirement in his appearing and his life, as necessarily to become the object of belief to every truth-loving, salvation-seeking spirit. In this command there is presupposed the impression, which the whole life of Christ must make upon him who contemplates it in the right spirit; the impression of Christ as designated and accredited by God himself, through the manner in which he dwelt in him and wrought in him. So also in the words of Christ just referred to, this is alleged as the ground on which God can require faith in him: "For him hath God the Father sealed;" the works which the Father had given him to perform being the tokens of that sealing. While it is here assumed on the one hand, that God has thus accredited him in whose name he requires belief, and therefore can require it; it is also presupposed that he has so formed the nature of men as that He cannot but make on them this divine impression, -- cannot but reveal himself as He to whom their God-allied nature attracts them, and in whom alone they can find satisfaction for all their higher wants; of whom their God-related nature itself bears undeniable testimony, that to him they belong, that he alone can free them from sin and all their misery, can alone impart that true life which they need. There is presupposed the original and continued connection of the God-related soul with the God in whom it lives and moves and is; and hence that drawing of the Father by which the souls of men are led to the Son. This command of God is, consequently, no other than what arises of itself from the relation of Christ to the human soul. It is no arbitrary requisition. What is required by the truth itself, by those divine historical facts, according as they do with the capacities and laws of human nature, with its deep-implanted wants, -- this here takes the outward form of a command of God. All this, however, whereby this command is shown to be the expression of an inward divine necessity, could be presupposed as already known, and needing no farther confirmation. For the Apostle was addressing churches already long established in Christianity; who had found, in their own experience, manifold evidences of the inward necessity of this belief. To such personal experience the Apostle makes his appeal in many passages of this Epistle. They had long known this as a command divinely enstamped upon their souls, constraining them to believe on the name of Jesus. Now as in this One command all others are included; so of necessity, as single commands to be enjoined each by itself, they are made superfluous. In that one command was bestowed, moreover, the ability to obey all others, -- the motive-power for the fulfilment of all which the Law requires. Thereby had the Law been converted from an outward to an inward law, having its root in the inner life. The Apostle, therefore, expresses only that one command; which, having for its basis faith in Jesus who had offered up his life for the salvation of man, contains all others in itself and renders them superfluous, -- the one command proceeding from Christ himself, LOVE ONE ANOTHER!