Ignorance of the difference between the law and the gospel promotes also, in a great degree, the strength and influence of a self-righteous temper. When a man is driven to acts of obedience by the dread of God’s wrath revealed in the law, and not drawn to them by the belief of His love revealed in the gospel; when he fears God because of His power and justice, and not because of His goodness; when he regards God more as an avenging Judge than as a compassionate Friend and Father; and when he contemplates God rather as terrible in majesty than as infinite in grace and mercy, he shows that he is under the dominion, or at least under the prevalence, of a legal spirit. If he builds his faith of the pardon of sin, of the favor of God, and of eternal life upon any graces which he supposes are implanted in him, or upon any duties which are performed by him, he is evidently under the power of the self-righteous temper. He shows that he is under the influence of his hateful temper by grounding his hope and comfort upon conditions performed by himself and not upon the gracious and absolute promises of the gospel. In a word, when his hope of divine mercy is raised by the liveliness of his frame in duties, and not by discoveries of the freeness and riches of redeeming grace offered to him in the gospel; or when he expects eternal life not as the gift of God through Jesus Christ, but as a recompense from God for his own obedience and suffering, he plainly shows, that he is under the power of a legal spirit. Now, if he is ignorant of the leading distinctions between the law and the gospel, this ignorance will strengthen his legal propensity and confirm him in his resolution to seek justification partly, if not wholly, by the works of the law.
John Colquhoun (1748–1827), A Treatise on the Law and the Gospel, 143–44 (HT: Inwoo Lee)