The general charge which Christianity gives to its adherents: “These things write I unto you, that ye sin not.” This is to repress presumption. This is the bearing not only of the writings of John, but of the whole Scriptures: this is the object at which every doctrine and every precept aims.

It may be thought, and has sometimes been said, that “all religions tend to make men better,” and, therefore, that this property of the apostle’s doctrine has nothing peculiar in it. But this is a gratuitous assumption. All religions do not tend to make men better; but, many of them, much worse. Nay, so far is this assumption from being true, that Christianity is the only religion that, strictly speaking, is opposed to sin. That men of all religions have paid some attention to morals, is true; but, in doing so, they have not been influenced so much by their religion as by the necessity which all men feel of maintaining somewhat of a correct conduct towards one another. As to sin against God, there is no religion but that of the Bible that pays any regard to it. And even Christianity itself, in so far as it is corrupted, loses this property. Every system of religion may be known by this whether it be of God or not. If it delight in calling sin by extenuating names—or represent repentance and good works as sufficient to atone for it—or prescribe ceremonial remedies for allaying the remorse which it produces—it makes light of sin, and is not of God. Every doctrine and precept in the Bible makes much of sin; and this is as much a distinguishing peculiarity of the true religion as any principle that can be named.

Some doctrines are directly of a warning nature. Are we taught, for instance, the omniscience and omnipresence of God?—What can be more pungent than such sentiments as these? “O Lord, thou hast searched me, and known me. Thou knowest my down-sitting and mine up-rising; thou understandest my thoughts afar off. Thou compassest my path, and my lying down, and art acquainted with all my ways. For there is not a word in my tongue, but, lo, O Lord, thou knowest it altogether. Thou hast beset me behind and before, and laid thine hand upon me.”—“Whither shall I go from thy Spirit? or whither shall I flee from thy presence? If I ascend up into heaven, thou art there;—if I take the wings of the morning, and dwell in the uttermost parts of the sea, even there shall thy hand lead me, and thy right hand shall hold me.” Every sentiment here saith to us, “Sin not.” Are we taught the holiness of God?—It is that we may be holy: “Who is like unto thee, O Lord, among the gods? who is like thee, glorious in holiness, fearful in praises, doing wonders?”—“Ye cannot serve the Lord: for he is a holy God; he is a jealous God; he will not forgive your transgressions nor your sins.” Such is the object of all the Divine precepts and threatenings. Let us seriously read the twenty-eighth chapter of Deuteronomy, and ask ourselves, What could induce the kindest and best of beings thus strictly to enjoin his will, and thus to scatter his curses against the breach of it? Finally, Such is the object of all the accounts of justice and judgments as executed on transgressors. The histories of the flood, of the burning of Sodom and Gomorrah, of the plagues of Egypt and the destruction of the Egyptians in the Red Sea, of the punishments on the rebellious Israelites in the wilderness, of the destruction of the city and temple of Jerusalem, first by the Chaldeans, and afterwards by the Romans, all speak one language; all are written to us that we “sin not.”

There is another set of Scripture truths which are of a consolatory nature; yet they are aimed at the same thing. For what purpose was the Son of God manifested in human nature? Was it not that he might “destroy the works of the devil?” To what are we elected? That we should “be holy, and without blame before him in love.” To what are we predestinated? That we might “be conformed to the image of his Son.” Why did he give himself for us, but that he “might redeem us from all iniquity, and purify unto himself a peculiar people, zealous of good works?” Why are we called out of a “state of darkness into his marvellous light, but that we might walk as children of light?” Of what use are the “exceeding great and precious promises” of the Scriptures? Is it not that, having them, we should “cleanse ourselves from all filthiness of the flesh and spirit, perfecting holiness in the fear of God?” That is not Christianity that does not operate in this way. He that sinneth habitually is of the devil, and hath not seen or known God. Wicked men seek a system of religion which may consist with their lusts; and God, in righteous judgment, often suffers them to find it; but it is not the gospel: the language of the gospel is, “These things are written to you, that ye sin not!”

The Scriptures guard the doctrine of grace, not indeed by limiting its operations to lesser sinners, but by insisting on its mortifying and sanctifying effects. The apostle Paul, notwithstanding all that he had written on justification by faith, exempts none from condemnation, but those that were “in Christ Jesus;” and admits none to be “in Christ Jesus,” but those who “walk not after the flesh, but after the Spirit.” He still declared, “If ye live after the flesh, ye shall die.” There is a universality pertaining to true holiness which distinguishes it from all that is spurious. We must be “holy in all manner of conversation,” or there is no real holiness in us. A single “wicked way” will lead to destruction. The certain perseverance of the saints is not that a person, having once believed, whether he depart from God or not, shall be finally saved; but that, God having put his fear in his heart, he shall not be suffered wholly to depart from him. If any man, therefore, depart utterly from God, he ought to conclude that the fear of God was not in him. If the blossom go up as the dust, the root was rottenness. If, in times of temptation, we fall away, it is because we have “no root in ourselves.” “If,” says the apostle John, “they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us.” Even our partial departures from God must render our state doubtful. When the Galatians doubted the gospel, the apostle stood in doubt of them; declaring he was afraid of them, lest he had “bestowed upon them labour in vain.” And had they judged according to evidence, as he did, they must have stood in doubt of themselves. To represent, as some do, that doubts and fears of this kind are the temptations of Satan, or the workings of unbelief, and require to be resisted, as that which is dishonourable to God, is to promote the most dangerous delusion, and to bring the blood of souls upon their own heads. The things which they call the temptations of Satan, may be found to be the dictates of an awakened conscience, which they endeavour to lull asleep. Doubts of the goodness or veracity of God, or of the all-sufficiency or willingness of the Saviour to receive those that come to him, are, indeed, dishonourable to God; but doubts of our own sincerity, founded upon our departures in heart and conduct from him, are so far from being sinful that they are necessary to awaken us to self-examination. Thus the Corinthians, who had sunk into many and great evils, were called upon, not to hold fast the persuasion that, notwithstanding this, their state was safe; but to “examine themselves whether they were in the faith, and to prove their own selves;” and assured that, except indeed they were reprobates, or disapproved of God, Jesus Christ was in them—that is, by his word and Spirit, bringing forth fruit.

Fuller, A. G. (1988). “Christianity the Antidote to Presumption and Despair,” Sermon XXIV. The Complete Works of Andrew Fuller: Memoirs, Sermons, Etc. (J. Belcher, Ed.; Vol. 1, pp. 322–324). Sprinkle Publications.