The truth is, though eternal life be the gift of God, yet eternal death is the proper wages of sin; and though faith is not represented in the above passage as the procuring cause of salvation, yet unbelief is of damnation. It is common for the Scriptures to describe those that shall be saved by something which is pleasing to God, and by which they are made meet for glory; and those that shall be lost by something which is displeasing to God, and by which they are fitted for destruction.
John 3:18, “He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.” Two things are here observable. First, Believing is expressive of saving faith, seeing it exempts from condemnation. Secondly, The want of this faith is a sin on account of which the unbeliever stands condemned. It is true that unbelief is an evidence of our being under the condemnation of God’s righteous law for all our other sins; but this is not all: unbelief is itself a sin which greatly aggravates our guilt, and which, if persisted in, gives the finishing stroke to our destruction. That this idea is taught by the evangelist appears, partly from his dwelling upon the dignity of the character offended, the “only begotten Son of God;” and partly from his expressly adding, “this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil.”
Luke 19:27, “But those mine enemies, which would not that I should reign over them, bring hither, and slay them before me.” If Christ, as wearing his mediatorial crown, has not a right to unreserved submission and hearty obedience, he has no right to be angry; and still less to punish men as his enemies for not being willing that he should reign over them. He has no right to reign over them, at least not over their hearts, if it be not their duty to obey him from their hearts. The whole controversy, indeed, might be reduced to an issue on this argument. Every sinner ought to be Christ’s friend, or his enemy, or to stand by as neutral. To say he ought to be his enemy is too gross to be defended. To plead for his being neutral is pleading for what our Lord declares to be impossible: “He that is not with me is against me.” There is, therefore, no room for any other position than that he ought to be his cordial friend; and this is the plain implication of the passage.
2 Thess. 2:10–12, “Whose coming is—with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved. And for this cause God shall send them strong delusion, that they should believe a lie: that they all might be damned who believed not the truth, but had pleasure in unrighteousness.” From hence we may remark two things: First, That faith is here called a receiving the love of the truth; and that it means saving faith is manifest, seeing it is added, “that they might be saved. Secondly, That their not receiving the love of the truth, or, which is the same thing, not believing with such a faith as that to which salvation is promised, was the “cause” of their being given up of God, and carried away with all deceivableness of unrighteousness. The loose and cold-hearted manner in which merely nominal Christians held the truth would occasion the introduction of the grand papal apostacy, by which great numbers of them would be swept away. And this, assuredly, ought to afford a lesson to nominal Christians of the present day, who, owing to the same cause, are fast approaching to infidelity. But unless we suppose that these professors of religion ought to have “received the love of the truth,” there is no accounting for the awful judgments of God upon them for the contrary.
Excerpt from: “God has threatened and inflicted the most awful of punishments on sinners, for their not believing on Jesus Christ,” Proposition V, Part II, in The Gospel Worthy of All Acceptation.
Fuller, A. G. (1988). The Complete Works of Andrew Fuller: Controversial Publications. (J. Belcher, Ed.) (Vol. 2, pp. 359–360). Harrisonburg, VA: Sprinkle Publications.