Paul asserts his love for the Hebrew nation, his "kinsmen according to the flesh," declaring that his conscience was "bearing him witness in the Holy Ghost." This strong asseveration implies an intimate relation between the Spirit and conscience. We may not be able to give a full and accurate statement of this relation. Among the self-evident truths with which the human mind is originally furnished is the distinction between right and wrong. The power to discover this distinction inheres in every sane mind. On questions relating to immutable morality all such minds agree in their decisions. Such questions are few, and theoretical rather than practical. They are not modified by circumstances. They are such as these: Is it right to hate a benefactor? Is it right to punish the innocent? Is it right to reward the guilty? Is it right to intend injustice to a fellow man? Is it right to violate my own sense of right? to dishonor a parent? to commit adultery? There can be but one answer to these questions. They are addressed to the intuitive sense of right and not to the understanding or practical judgment which modifies the decision. But when we ask the question, Is this accused man worthy of punishment? we have now to exercise our judgment and go through a course of reasoning before we can decide, and two perfectly conscientious persons may disagree in their verdict, because we are now in the region of mutable morality. Most of the moral questions in daily life are of this character. It is not enough to know that one man has killed another. I must take into account the circumstances, whether it was in self-defense when attacked by a robber, or a burglar by night was shot in the act of breaking into the dwelling. This sufficiently illustrates mutable morality.
I can but think that the philosophy of Lotze and others is true, that all the self-evident truths are in the last analysis the activity of the immanent God in the human spirit. Hence the moral intuitions, immutable and invariable, are the voice of the divine Spirit immanent in all men, irrespective of regeneration and the gracious indwelling of the Spirit. There is a sense in which the Spirit of God is upholding nature. Men are not conscious of this immanent substratum of their being. But when the Holy Spirit, as a gracious gift, is bestowed upon the believer, he is conscious of His presence within as was Paul. The effect is manifest not so much in the increase of the power of moral discrimination, though it does clarify the moral perceptions, as in the marvelous addition to the power that impels toward righteousness. For the conscience has a threefold power discrimination, impulse toward the right, and, after the act, approval or disapproval, according as the act is right or wrong. The gracious work of the Holy Spirit intensifies each of these functions, the second more manifestly than the first, and the third more than the second.
What effect does the fulness of the Spirit have in the decisions of practical questions in the province of mutable morality? We answer, it does not prevent errors in judgment and fallacies in logic. The Holy Spirit renders no one infallible in such matters. Yet He indirectly helps us by delivering us from the dominance of appetites and passions inimical to clearness of intellect and calmness of judgment. By inspiring in our hearts love to our neighbor as to ourselves, He strongly incites us to do perfect justice to him in our decision of questions involving his rights. Still the best of men and women who love God with all their hearts, and their neighbors as themselves, may go astray in judgment without a loss of love. Hence, in applying their intellects to the construction of systems of theology, some have founded Calvinism with its five points, unconditional election, a limited atonement, irresistible grace, bound will, and the final perseverance of the saints; and others equally devout and scholarly have constructed Arminianism with its universal atonement conditionally applied, the free will, entire sanctification possible before death, and the peril of a total apostasy from the highest state of grace. George Whitefield preached the first of these doctrines and John Wesley the last. Both were filled with the Spirit and were burning as bright candies of the Lord. Both were used by the Spirit to preach the saving truths of the gospel in such a way as to save multitudes of souls.
— edited from The Gospel of the Comforter, Chapter 19.