The Ten Commandments are the beginning of the Mosaic Law code that was given specifically to Israel as a redeemed people (Lev 27:34), and they were not given in written form to anyone else. The Ten Commandments not only revealed the holy character of God, but gave the Israelites an objective standard for right living, both before God and others. Though the Law was given specifically to Israel, there is a sense in which God’s Laws are written on the hearts of all people, even those who are not saved. Paul wrote, “For when Gentiles who do not have the Law do instinctively the things of the Law, these, not having the Law, are a law to themselves, in that they show the work of the Law written in their hearts, their conscience bearing witness and their thoughts alternately accusing or else defending them” (Rom 2:14-15). Warren Wiersbe writes:
- "God did not give the Law to the Gentiles, so they would not be judged by the Law. Actually, the Gentiles had “the work of the Law written in their hearts” (Rom 2:15). Wherever you go, you find people with an inner sense of right and wrong; and this inner judge, the Bible calls “conscience.” You find among all cultures a sense of sin, a fear of judgment, and an attempt to atone for sins and appease whatever gods are feared."
According to Paul, God has placed His Law within the heart of every person, which Law informs us concerning God’s standard of what is right; and, God has given every person a conscience. The word conscience translates the Greek word συνείδησις suneidesis, which refers to “the inward faculty of distinguishing right and wrong.” Conscience does not instruct us concerning what is good or evil, for that is determined by God; rather, conscience is that inner voice that urges us to do right. However, because of sin’s corrupting influence, the human conscience it is not always a reliable gauge of right and wrong. It would seem that conscience functions cognitively in a judicial role, evaluating thoughts and actions and determining guilt or innocence based on moral laws. This would make sense, as Paul describes the conscience as “bearing witness” with regard to some behavior, and the mind serving as the courtroom, “accusing or defending” the action.
Human conscience, when operating properly, serves as God’s moral compass placed within each person. People instinctively know that God exists (Rom 1:18-20), and that the Law of God is good (Rom 2:14-15). We don’t have to persuade anyone. It’s already written on their hearts. God placed it there. They know God exists, that He is good, and that actions such as murder, lying, stealing, and adultery are wrong.
Those who have a relationship with God and pursue a life of faith will have a healthy conscience that operates as God intends. This starts when “the blood of Christ…cleanses our conscience” so that we may “serve the living God” (Heb 9:14). In the New Testament Paul spoke of the “good conscience” that was connected with “genuine faith” (1 Tim 1:5, 19; cf. Acts 23:1; Heb 13:18), and he personally served God with a “clear conscience” (1 Tim 3:9; 2 Tim 1:3). Paul also described believers at Corinth whose “conscience is weak” (1 Cor 8:7, 10, 12). These were immature believers whose consciences had been corrupted by years of sinful living before their conversion and who had not fully restored their conscience to normal operation. Learning God’s Word recalibrates our conscience, and advancing spiritually strengthens it. In a negative way, there are some who progressively turn away from God and indulge in sin, and whose “conscience is defiled” (Tit 1:15), or who have “an evil conscience” (Heb 10:22). Paul wrote of some “whose consciences have been seared as with a hot iron” (1 Tim 4:2). The word seared translates the Greek word καυστηριάζω kausteriazo, which means to burn or cauterize with a hot iron. Just as one’s flesh can be severely burned so that it becomes hard, without sensitivity, so the conscience can become hardened and without feeling. This is obvious in the person who lives in prolonged sin and no longer blushes at their wicked behavior. I once knew a man in prison who bore the moniker “Naughty.” I once heard this man boast, with smile and laughter, of having sexually abused a helpless woman whom he greatly degraded, and he did this without any remorse. I cringed as others laughed at his stories. Here were consciences that had become seared because of sinful behavior.
The believer, though having a conscience damaged by years of sin, can have it cleansed by means of the cross-work of Christ, and then recalibrated by means of God’s Word, which provides an objective standard for righteousness. But this will not happen quickly. Just as we exposed ourselves to many years of worldly thinking, which corrupted our consciences, so it will take time to unseat the human viewpoint and restore the conscience to normal function as God intends.
 Warren W. Wiersbe, The Bible Exposition Commentary, vol. 1 (Wheaton, IL: Victor Books, 1996), 520.
 William Arndt et al., A Greek-English Lexicon of the New Testament and Other Early Christian Literature (Chicago: University of Chicago Press, 2000), 967.
 The “blood of Christ” refers to Jesus atoning work on the cross, in which He bore our sin and paid the penalty that rightfully belonged to us. This was in contrast to the OT sacrificial system which could never take away sin, only cover it for a short time. When we believe in Christ as Savior (1 Cor 15:3-4), we are forgiven all our sins (Eph 1:7), given new life (John 10:28), and gifted with God’s own righteousness (2 Cor 5:21; Phil 3:9). At the moment of salvation, there is relational peace between us and God (Rom 5:1), and we have become part of His family (Eph 2:19), will never be condemned (Rom 8:1), and made free to serve Him in righteousness (Rom 6:11-14; Tit 2:11-14). In this way, the “blood of Christ” has cleansed our conscience from any notion that religious.