"The goal … is love, which comes from a pure heart and a good conscience …" (1 Tim. 1:5).
How does the conscience work? There has been much debate in theological circles concerning exactly what the conscience is and how it works. Some say it functions in the rational faculty of the soul, while others, such as the Puritan Richard Sibbes, maintain that the conscience involves the activity of the entire soul—the mind, will, and emotions. While this debate may seem like hairsplitting, it does hold some relevance in understanding how to penetrate and refine the conscience. Do you appeal to people’s emotions to stimulate the conscience? Do you simply try to change their behavior while ignoring their knowledge of right and wrong? Or do you inform the mind so that the whole person might be transformed—as Paul said, “Be transformed by the renewing of your mind”? Those who maintain that the conscience functions in the rational faculty of the soul would say that right knowledge is paramount in establishing right behavior.
Thomas Aquinas called the conscience man’s judgment of himself according to God’s judgment of him. The Puritan Thomas Goodwin said the “conscience is one part of the practical reason … (which guides us in our actions in general of any kind.)” The conscience is equipped with the knowledge of God’s law, which is written into the fabric of our being. This natural law, as it is called, is reinforced and strengthened by the revealed law of God in the Scriptures. The conscience uses this knowledge as well as knowledge about one’s self to form judgments. Hence, the soul, as Sibbes put it, reflects upon itself. It forms two premises. The first premise is the law or rule according to God’s law, and the second is a fact about oneself. A conclusion that will either defend and comfort, or accuse and condemn is then formed from these premises. This is how the conscience works: Premise 1: It is a sin to lie. Premise 2: I have lied. Conclusion: I have committed a sin. This construction is called a practical syllogism. By this method, the conscience informs you of God’s judgment—whether you’re guilty or innocent. While this example is very simple, the conscience can be very complex, taking into account not only God’s law but His promises as they apply to you.