Stephen Charnock wrote, in his sermon "A Discourse of the Word, the Instrument of Regeneration," the following as it relates to the efficient and instrumental causes of regeneration. These citations refute the argumentation of Jason Brown, Hardshell apologist, wherein he argued that the instrumental cause must be viewed as the efficient cause.
"The Scripture does distinguish the efficient and instrumental cause by the prepositions "ek", or, "eks", and "dia". When we are said to be 'born of the Spirit,' it is, John iii. 5, "ek pneumatos"; 1 John iii. 9, v. 1, "ek Theou"; never "dia pneumatos", or "dia Theou:" but we are nowhere said to be born of the word, or begotten of the word, but "dia logou", by or with the word, 1 Peter i. 23; and "dia euangeliou", 1 Cor. iv. 15, I have begotten you 'through the gospel.' The preposition "ek" or "eks", usually notes the efficient or material cause; "dia", the instrumental or means by which a thing is wrought."
"As God will have the mediation of his Son honoured in the whole progress and perfection of grace as the meritorious cause, the efficacy of the Spirit as the efficient cause, so he will have the word in every step to heaven honoured as the instrumental cause; that as Jesus Christ is all in all, as the chief, so the word may be all in all as the means. As God created the world by the word of his power, and by the word of his providence bid the creatures increase and multiply, so by the word of the gospel he lays the foundation, and rears the building, of his spiritual house."
"Consider, as it is an instrument, so but an instrument. God begets by the word; the chief operation depends upon the Spirit of God. No sword can cut without a hand to manage it, no engine batter without a force to drive it. The Word is objective in itself, operative by the power of the Spirit; instrumental in itself, efficacious by the Holy Ghost. The Word of Christ is first spirit and then life. 'The words that I speak unto you, they are spirit and they are life,' John vi. 63...When it is received into the speculative understanding, it is a preparation to the new birth; when it is received into the practical understanding and will, it is the new birth...The Spirit immediately himself touches the soul, but by the word, as an instrument proposing the object, and drawing out the soul into an actual believing."
"Some word or other was the instrument to beget you (I speak of people grown up). The apostle's interrogation is a strong negative. There is no believing without hearing, Rom. x. 14. Hearing goes before believing; he lays it down as a certain conclusion from his former arguing: 'So then faith comes by hearing, and hearing by the word of God.' If you conclude yourselves new begotten, how came you by it? Is it by the word, or no? That is God's ordinary means. If you be not renewed by this, it is not likely you are renewed at all; no other instrument has God ordinarily appointed to this end. Afflictions may plough men for it, but the word is the only seed that renews the face of the earth. All false notions or presumptions of the new birth must be brought to this touchstone; it is a misshapen and monstrous birth, that is not by a seed of the same kind; the law in the heart has no seed of the same nature with it to engender it, but the law in the word, that word which we properly call gospel; the word of truth, not the word of philosophy, which is a word of uncertainty; God's word, not Plato's word."
"The gospel, the word of truth, does much more than this: it is an instrument to beget a soul for God; an instrument whereby God makes himself our Father, and us his children. It is but an instrument; let not the glory be given to the instrument, but to the agent." (see here)
John Gill, in commenting upon Romans 11: 14, asserts the same:
"The ministers of the Gospel may be said to save souls, not efficiently, for the author or efficient cause of salvation is God only; the Father has chose unto it, the Son has effected it, and the Spirit applies it; but instrumentally, as the word preached by them is the means of regeneration, faith, and conversion, with which salvation is connected: and as they show unto men the way of salvation, and encourage souls to believe in Christ, in whom alone it is."