Revelation 3:20

“Behold, I stand at the door, and knock: 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.”

John Owen (1616-1683)

Towards his elect not yet effectually called. Rev. iii. 20, he stands waiting at the door of their hearts and knocks for an entrance. He deals with them by all means, and yet stands and waits until “his head is filled with the dew, and his locks with the drops of the night,” Cant. v. 2; as enduring the cold and inconveniences of the night, that when his morning is come he may have entrance. Oftentimes for a long season he is by them scorned in his person, persecuted in his saints and ways, reviled in his word, whilst he stands at the door in the word of his patience, with his heart full of love towards their poor rebellious souls.

(From: “Works”)

Francis Turretin (1623-1687)

Although God is said “to stand at the door” (Rev. 3:20) and to “knock,” it does not follow that man has the power to open it of himself. Either he stands by the regenerate and knocks that they may use the grace already bestowed to open it by faith and obedience; or by the unregenerate who are either elected (to whom by knocking he gives by the Spirit the strength to open) or the reprobate (whose heart is not knocked at in vain, but in order to manifest that man is justly condemned, since God has withheld none of those things which conduce to conversion).

(From: “Institutes of Elenctic Theology”)

When it is said “Christ stands at the door and knocks” (Rev. 3:20), it cannot be inferred that sufficient grace is granted to all. (1) He is there treating of those already called who were in the church, not of those about to be called. (2) That standing and knocking not only designates internal notions, but is properly referred to external exhortations (which are made partly by the word, partly by afflictions) of which he had spoken in the preceding verse. Therefore he knocks in different ways at the hearts of the elect and reprobate; at the former externally and internally by the word and by the Spirit so that, by knocking imperatively by the word, he may also open them operatively by the Spirit (as was the case with the heart of Lydia). At the latter, however, he only knocks externally by the word that they may understand their duty, the promised benefit, the heinousness of their sin and the justice of punishment if they neglect the voice of God. Nor is it absurd for God to knock, although he knows that man will not open. He does not cease justly to admonish man of his duty and to convict the rebellious of obstinacy.

(From: “Institutes of Elenctic Theology”)