I shall content myself with three reasons. The first taken from the damning nature of false doctrine; the second from the subtlety of seducers to draw into false doctrine; and the third from the universal influence that an established judgment hath on the whole man, and whole course of a Christian.
Reason First. From the damning nature of false doctrines. They hunt for the precious life of souls, as well as any other sin. An imposthume in the head proves oft as deadly as one in the stomach. A corrupt judgment in foundation-truths kills as sure as a rotten heart. Indeed, it proceeds thence. Jezebel’s children are threatened to be to be ‘killed with death,’ Rev. 2:23. And who are her children, but her disciples, that drink of her cup of fornication and embrace her corrupt doctrines? But sure this is not believed by some, who, though very strict in their lives, and seem as tender in matter of morality as Lot was of his guests, yet are very loose in their principles and judgements, exposing them, as he his daughters, to be defiled with any corrupt doctrine that comes to their door. They would make us think, that here men played but at small game, and their souls were not at stake, as in other sins. As if there were not such a question to be asked at the great day—what opinions we held? and whether we were sound in the faith?—in a word, as if false doctrines were but an innocent thing, not like the wild gourd which brought death into the prophets’ pot, II Kings 4:39, 40—turning wholesome food, with which it was mingled, into baneful poison—but rather like herb-john in the pot, that does neither much good nor hurt. Yea, there be some that speak out, and tell us a man may be saved in any religion, so he doth but follow his light. And are not these charitable men? Because they would have the company as few as may be that are damned, [they] make as many roads to heaven as the Scripture tells us are ways to hell? This is contrary to the teaching of Christ, who tells us of no other way but by him to life. ‘I am the way, the truth, and the life,’ John 14:6. It is point blank against St. John, who tells us of but one doctrine, and that the doctrine of Christ, and that he that holds not this to be marked out for a lost man. ‘Whosoever transgresseth and abideth not in the doctrine of Christ, hath not God,’ II John 9, 10. And how far, I pray, is that man off hell that hath not God? Him that hath not God before he dies, the devil shall have when he dies. Well, sirs, the time is coming, yea it hastens—what favour and kindness soever corrupt doctrines find here at man’s hand—wherein the obstinate heretic shall receive the same law at Christ’s hands with the impenitent drunkard. You may see them both under the same condemnation, as they stand pinioned together for hell, Gal. 5:20, 21, ‘I tell you now,’ saith the apostle, ‘as I have told you in time past, that they which do such things, shall not inherit the kingdom of God.’ And see, I pray, if you cannot find the heretic’s name amongst them? Ignorance in fundamentals is damning, surely then error in fundamentals much more. If a pound weighs down the scale, there is no doubt then but a stone-weight will do it. If the less sin presseth down to hell, how can we rationally think that the greater should escape it? Error stands at a farther distance from, yea at a fuller contrariety to, truth than ignorance. Error is ignorance with a die on it. He that eats little or nothing must needs die, much more he that eats rank poison. The apostle doth not only tell us of ‘pernicious ways,’ and ‘damnable heresies,’ but he tells us they ‘bring swift destruction’ upon those that hold them, II Peter 2:1, 2. I pray observe what an accent he lays on the destruction that comes by these corrupt doctrines, he calls it ‘swift destruction.’ All rivers find their way at last to the sea from whence they sprang, but some return with a swifter stream, and get sooner to it, than others. Would any make it a shorter voyage to hell than ordinary, let him throw himself but into this stream of corrupt doctrine, and he is not like to be long in going.
Reason Second. Because impostors are so subtle, it therefore behoves the Christian to establish and strengthen his judgment in the truths of Christ. They are a generation of men skilful to destroy the faith of others. There is an erudita nequitia in the world, as one calls it, a learned kind of wickedness, that some have to corrupt the minds of men. The Spirit of God sets them out to life, sometimes comparing them to merchants, who can set a gloss upon their false ware with fine words; they are said, II Peter 2:3, ‘with feigned words’ to ‘make merchandise’ of souls—sometimes to hucksters, that blend and dash their wine with water, II Cor. 2:17—sometimes to cheating gamesters, that have a sleight of hand to cog the die, Eph. 4:14—yea, to witches themselves: ‘Who hath bewitched you?’ saith the apostle, Gal. 3:1. Strange things have been done in our days on those that God has suffered them to practice their sorcery upon; and what counter-charm better than an established judgment? It is observable that in II Tim. 3:8, where the apostle compares the seducers of that present age to those sorcerers Jannes and Jambres, that resisted Moses, and shows what kind of persons they were that fell into their snare —such as though ‘ever learning,’ yet never came ‘to the knowledge of the truth,’ ver. 7, he then turns to Timothy [with the words], ‘But thou hast fully known my doctrine,’ ver. 10. As if he had said, I am out of fear for thee;—thou art better grounded in the doctrine of the gospel, than to be thus cheated of it. Indeed, those whom seducers lie in wait for, are chiefly weak unsettled ones; for as Solomon saith, ‘In vain the net is spread in the sight of any bird,’ Prov. 1:17. The devil chose rather to assault Eve than Adam, as the more likely of the two to be caught; and ever since he takes the same course. He labours to creep over where the hedge is lowest, and the resistance likely to be weakest.