That the power of the gospel in the hearts of believers is the power of the Holy Spirit is admitted. All that the gospel effects is to be attributed to the Holy Spirit, who works by it as a means. It is called “the sword of the Spirit,” Eph. 6:17; its influence, therefore, is as much the influence of the Spirit as that of a sword is of the hand that wields it. That obedience to the truth by which our souls are purified is “through the Spirit,” 1 Pet. 1:22. Indeed all the means, whether ordinances or providences, or whatever is rendered subservient to the sanctification and salvation of the souls of men, are under the direction of the Holy Spirit. The influence, therefore, which they have to these ends is reckoned his influence. But it does not follow from hence that “the power of the gospel is in no sense to be distinguished from the power of the Holy Spirit, or that the one is always connected with the other, or that they both necessarily, and in all cases, include one and the same Divine operation.” The contrary of each of these positions appears to be the truth. The passages already adduced speak of the influence of the word upon those, and those only, who believe; and then the question is, How is it that a sinner is brought to believe?
The word of God cannot, in the nature of things, operate effectually till it is believed; and how is this brought about? Here is the difficulty. Belief, it may be said, in other cases is induced by evidence. This is true; and if the hearts of men were not utterly averse from the gospel, its own evidence, without any supernatural interposition, would be sufficient to render every one who heard it a believer. But they are averse; and we all know that evidence, be it ever so clear, will make but little impression upon a mind infected with prejudice, The Scriptures speak of “sanctification of the Spirit, and the belief of the truth,” as distinct things; and as if the one was antecedent to the other, 2 Thess. 2:13. They also tell us that “the Lord opened the heart of Lydia, and she attended to the things which were spoken by Paul.” We are said to “believe, according to the working of his mighty power, which he wrought in Christ when he raised him from the dead,” Eph. 1:19, 20. It would not require more power to believe the gospel than any other system of truth, if the heart were but in harmony with it; but as it is not, it becomes necessary that a new bias of heart should be given as a preparative to knowing or embracing it. The Scriptures not only speak of knowledge as the means of promoting a holy temper of heart, but of a holy temper as the foundation of true knowledge. “I will give them a heart to know me, that I am the Lord,” Jer. 24:7.
If it be objected that “faith comes by hearing, and hearing by the word of God,” I answer that faith must have an object, or it cannot exist. The word of God is the objective cause of faith; but it does not follow from hence that it is its sole or compulsive cause. Eating cometh by food, and food by the blessing of God upon the earth. Food may be said to be the objective cause of a man’s eating, seeing he could not have eaten without food; but it does not therefore follow that food was the impulsive or sole cause of his eating; for had he not been blessed with an appetite, he would not have eaten, though surrounded by food in the greatest plenty.
If it be further objected that we can form no rational idea of the influence of the Holy Spirit, any otherwise than as through the medium of the word; I answer, we can form no idea of the influence of the Holy Spirit at all, either with or without the word, but merely of its effects. We may indeed form an idea of the influence of truth upon our minds, but we cannot conceive how a Divine influence accompanies it. Nor is it necessary that we should, any more than that we should comprehend “the way of the Spirit,” in the quickening and formation of our animal nature, in order to be satisfied that we are the creatures of God. It is sufficient for us that we are conscious of certain effects, and are taught in the Scriptures to ascribe them to a Divine cause.
Excerpt from: “Power and Influence of the Gospel,” in Answers and Queries.
Fuller, A. G. (1988). The Complete Works of Andrew Fuller: Expositions—Miscellaneous (J. Belcher, Ed.; Vol. 3, pp. 775–776). Sprinkle Publications.