Therefore it is easy to discern their error, that tell men the light or Spirit within them, is their rule, and a perfect rule, yea, and that it is thus in all men in the world; when God's word and experience flatly contradict it, telling us that infidels and enemies of God, and all the ungodly, are in darkness, and not in the light; and that all that speak not according to this word, (the law and testimony,) have "no light in them;" and therefore no "perfect light to be their rule," Isa. viii. 20. The ministry is sent, to bring them from darkness to light: therefore, they had not a sufficient light in them before, Acts xxvi. 17, 18. "Woe to them that put darkness for light, and light for darkness!" Isa. v. 20: telling the children of darkness, and the haters of the light, that they have a perfect light and rule within them, when God saith, "They have no light in them." See 1 John i. 4-8. "He that saith he is in the light, and hateth his brother, is in darkness even till now," 1 John ii. 9-11. The light within a wicked man, is "darkness" and "blindness," and therefore not his rule, Matt. vi. 23; Eph. v. 8. Even the light that is in godly men, is the knowledge of the rule, and not the rule itself at all, nor ever called so by God. Our rule is perfect; our knowledge is imperfect: for Paul himself saith, "We know in part; but when that which is perfect is come, then that which is in part shall be done away: now we see through a glass darkly," 1 Cor. xiii. 9, 10, 12. "The gospel is hid to them that are lost," being "blinded by Satan," 2 Cor. iv. 3, 4.
There is an admirable, unsearchable concurrence of the Spirit, and his appointed means, and the will of man, in the procreation of the new creature, and in all the exercises of grace, as there is of male and female in natural generation; and of the earth, the sun, the rain, the industry of the gardener, and the seminal virtue of life and specification, in the production of plants with their flowers and fruits. And as wise as it would be to say, it is not the male but the female, or not the female but the male that generateth; or to say, it is not the earth but the sun, or not the sun but the rain, or not the rain but the seminal virtue, that causeth plants with flowers and fruits: so wise is it to say, it is not the Spirit but the word and means, or it is not the word and means but the Spirit, or it is not the reason, and will, and industry of man, but the Spirit: or, if we have not wisdom enough to assign to each cause its proper interest in the effect, that therefore we should separate what God hath conjoined, or deny the truth of the causation, because we comprehend not the manner and influence--this is but to choose to be befooled by pride, rather than confess that God is wiser than we.
2. You may here discern also, how the Spirit assureth and comforteth believers: and how palpably they err, that think the Spirit comforteth or assureth us of our salvation without the use of its evidencing grace. The ten things mentioned above, is all that the Spirit doth herein. But to expect his comforts without any measure of discerning his graces, which can only rationally prove our right to the blessings of the promise, this is to expect that he should comfort a rational creature not as rational, but darkly cause him to rejoice he knoweth not why: and that he should make no use of faith to our comfort: for faith resteth understandingly upon the promise, and expecteth the performance of it to those that it is made to, and not to others. Indeed there is a common encouragement and comfort, which all men, even the worst, may take from the universal, conditional promise: and there is much abatement of our fears and troubles that may be fetched from probabilities and uncertain hopes of our own sincerity and interest in the promise. But to expect any other assurance or comfort from the Spirit, without evidence, is but to expect immediate revelations or inspirations to do the work, which the word of promise and faith should do. The soul's consent to the covenant of grace, and fiducial acceptance of an offered Christ, is justifying, saving faith: every man hath an object in the promise and offer of the gospel for this act, and therefore may rationally perform it. (Though all have not hearts to do it.) This may well be called, faith of adherence; and is itself our evidence, from which we must conclude, that we are true believers: the discerning of this evidence, called by some, the reflex act of faith, is no act of faith at all, it being no believing of another, but the act of conscience, knowing what is in ourselves. The discerning and concluding that we are the children of God, participateth of faith and conscientious knowledge, which gave us the premises of such a conclusion.