Behold, I stand at the door, and knock; behold, I have stood ( ἕστηκα) at the door, and am knocking ( κρούω). "These gracious words declare the long-suffering of Christ, as he waits for the conversion of sinners (1 Peter 3:20); and not alone the long-suffering which waits, but the love which seeks to bring that conversion about, which 'knocks.'
He at whose door we ought to stand, for he is the Door (John 10:7), who, as such, has bidden us to knock (Matthew 7:7; Luke 11:9), is content that the whole relation between him and us should be reversed, and instead of our standing at his door, condescends himself to stand at ours" (Trench).
The view, that stand at the door signifies "to come quickly" (Dusterdieck), as in Revelation 2:5, Revelation 2:16; Revelation 3:3, Revelation 3:11, is scarcely in accordance with the context, since the whole passage has changed from rebuke and menace to patient beseeching and loving exhortation.
These words recall the frequent use by our Lord of this figure of knocking, and especially Luke 12:35, Luke 12:36, "Let your loins be girded about, and your lights burning; and ye yourselves like unto men that wait for their lord, when he will return from the wedding; that when he cometh and knocketh, they may open unto him immediately."
If any man hear my voice, and open the door, I will come in to him, and will sup with him, and he with me (see the parallel passage in Song of Solomon 5:1-16.). Christ knocks and speaks. A distinction has been drawn in the work of conversion, corresponding to these two actions.
The knocking is likened to the more outward calls of sickness, trouble, etc., by which he makes his presence known; while the voice, which interprets the knock and informs us of the Personality of him who knocks, is the voice of the Holy Spirit, speaking to us, and explaining the meaning of our trials.
Man's free will is here well and plainly set forth. Though the opening, to be effective, needs the help and presence of Christ, yet he does not forcibly effect an entrance; it is still within the power of man to disregard the knock, to refuse to hear the voice, to keep the door fast shut.
To take food with any one is an outward sign of brotherly love and reconciliation. Christ will sup with those who do not drive him away, and they will sup with him. The whole figure is an image of the perfect nature of the sinner's reconciliation with God, and of the wonderful goodness and condescension of Christ.
But we may well see an allusion to the Holy Communion, by which we are reconciled to God through Christ, and by which we may even now have a foretaste of the final supper of the Lamb, which shall eventually last for ever.