"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.[Behold, I stand at the door, and knock.] Christ called this Church, her Elders and Members, to consider how unwilling he was to leave them, to forsake them, and cast them off , if they would take his counsel and amend. Behold, that is, observe well what I have yet further to say to you, ere I depart from you. [I stand at the door, and knock.] Christ knocks at the door of our Hearts by the powerful Operations of his holy Spirit, as 1 Thess. 1. 4, 5. and Heb. 4. 12. Christ continued his presence still with this Church, notwithstanding their luke-warmness, (as he did of old, Hos. 6. 4-9. and Hos. 11. 1-4-7, 8, 9-12. How shall I give thee up Ephraim? — How shall I make thee as Admah? how shall I set thee as Zeboim? mine heart is turned within me, my repentings are kindled together;) because, First, Christ knew some of those luke-warm ones were elect ones, whom the Father had given unto him, John 6. 37, 38, 39, 40. and 2 Tim. 2. 19. and John 10. 16. or else Christ doth this to leave them without excuse, Rom. 1. 20. and Heb. 2. 1, 2, 3.[If any man hear my voice, and open the door.] That is in the Ministry of the Word, and open the door of his heart, by a willing consent to accept his offers of Grace upon Gospel-Terms. [I will come in to him, and will sup with him and he with me.] This is a great encouragement unto them to answer his earnest desire, and gracious Invitation to open their Hearts, and to admit him entrance, by promising them, First, Union with him; [I will come in to him.] Secondly, Communion with him; [and sup with him, and he with me.] By supping together, we may understand the mutual fellowship between Christ and their Souls, in the sacred Ordinances of God, 1 John 1. 3."
According to the above material, Knollys thinks that the gospel is an "offer of grace" and a "gracious invitation" wherein Christ "earnestly desires" sinners to "open their hearts" and "admit him entrance." In other words, Christ wills for all of those in the visible church [according to Knollys' covenantal ecclesiology] that hear the external call [the "Ministry of the Word"] to comply with the gospel terms/commands.
A brief bio on Knollys at CCEL says:
"In London he was instrumental in the formation of a baptist church at Great St. Helen's, Bishopsgate. Knollys took part with Kiffin and Keach in many baptist endeavours. Knollys was one of the seven men who sent out the invitation to the 1689 General Assembly. Two years after he had subscribed the 1689 London Baptist Confession of Faith, he was called to his Master."