The conscience is the capacity to discern between good and evil. The conscience is found in the heart or what one might call our spiritual being. Solomon asks God, “Therefore give to Your servant an understanding heart to judge Your people, that I may discern between good and evil.” An understanding heart granted Solomon the capacity to discern between good and evil, thus the conscience is connected with the heart. Hebrews 10:22 confirms its location in the heart, “let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience and our bodies washed with pure water.” The blood of Jesus Christ is sprinkled on the heart of a Christian thus cleansing them from an evil conscience. So the conscience is located in the heart or the spiritual person. The conscience is not a natural arbiter of good and evil. While everyone possesses the raw capacity to discern right and wrong, the conscience must be trained to identify each. The ultimate educator of the conscience is God’s word. “I will instruct you and teach you in the way you should go; I will guide you with My eye,” the Lord says in Psalm 32:8. “Who is wise,” the Lord asks in the final verse of Hosea, “Let him understand these things. Who is prudent? Let him know them. For the ways of the LORD are right; The righteous walk in them, But transgressors stumble in them.” A conscience trained by God’s word acts as an internal mechanism that deters us from evil and compels us toward good.
In Romans 2:15, Paul talks of a conscience which either accuses or excuses one’s conduct. When we commit an immoral act and recognize its immorality, our conscience feels guilty – it accuses us of wrong doing. Adam and Eve covered their nakedness and hid from God. David felt guilty after stealthily cutting a corner off of Saul’s robe. Those Jews who believed Peter’s testimony on Pentecost were cut to the heart. These are examples of consciences which accused their possessors of wrong doing (a guilty or evil conscience). On the flip side a conscience that excuses – which the NT writers often call a good or pure conscience – is one which is at peace with itself, where this mechanism is not accusing us of wrong doing. A good conscience is achieved when one’s external actions agree with their internal motivations. The English word conscience comes from the Greek word “suneidesis” (soon-i'-day-sis), a compound word whose fundamental idea is “knowing together with one’s self.” As one man wrote, “To have a good conscience is to be able to look in the face the knowledge which one shares with no one but oneself and not be ashamed.” The Hebrew writer requests, “Pray for us, for we are sure that we have a good conscience, desiring to conduct ourselves honorably in all things.” (Hebrews 13:18) A good or pure conscience exists when one does the right things for the right reasons.
Living with a good conscience does not always indicate a righteous life. In Acts 23:1 Paul said to the Sanhedrin, "Men and brethren, I have lived in all good conscience before God until this day." This is an astounding statement since in it he includes his life prior to the Damascus road when he persecuted the church of God beyond measure and tried to destroy it. Yet he claims to have done so “in all good conscience before God,” later stating in Acts 26:9, “I myself was convinced that I ought to do many things in opposing the name of Jesus of Nazareth.” How could a good conscience engage in such evil activities and yet be absolved of guilt? Because he “was convinced” that his actions were right; he believed he was serving God. Jesus warns in John 16:2, “They will put you out of the synagogues; yes, the time is coming that whoever kills you will think that he offers God service.” Paul was persuaded that he was serving God which is why he could say, “I have lived in all good conscience before God until this day.” Paul demonstrates that it is possible to be sincerely wrong: Paul was convinced he was doing what was right but opposed God in his conduct.
Perpetual sin hardens the conscience. Paul exhorts us to “no longer walk as the rest of the Gentiles walk.” Those who remain in that condition are “past feeling,” literally they have ceased to feel pain. (Ephesians 4:17-19) Sin hardens the conscience until it no longer feels the pang of guilt. The Lord says that Judah was so immersed in sin, “They were not at all ashamed, nor did they know how to blush.” (Jeremiah 6:15) Paul says those who abandon the faith have “their own conscience seared with a hot iron.” Sin cauterizes the conscience making it dead to sensation. A silent conscience does not necessarily indicate that one is living a righteous life.
The sacrifice of Jesus offers what other sacrifices cannot – the cleansing of a conscience racked with the guilt of sin. The blood of Christ cleanses our conscience from dead works (Hebrews 9:14). This is possible because Christ’s sacrifice secures eternal redemption. Christ’s sacrifice is eternal since it is a single sacrifice which pays for all mankind’s sins (verse 28, “so Christ was offered once to bear the sins of many.”). But most importantly for our conscience, it is eternal in this sense: that once sin is removed from our record, it is permanently removed, never to be remembered by God again. Hebrews 8:12 (which quotes Jeremiah 31:34) states a promise for those who live under the New Covenant, “FOR I WILL BE MERCIFUL TO THEIR UNRIGHTEOUSNESS, AND THEIR SINS AND THEIR LAWLESS DEEDS I WILL REMEMBER NO MORE.” When we humbly come to the throne of grace, confess our sins, and change our ways, that sin is removed from our record, never to be remembered by God again.
Peter teaches us that the cleansing of the conscience begins in baptism. Baptism is, “not the removal of dirt from the flesh, but an appeal to God for a good conscience.” (1 Peter 3:21) Unlike the rites ordained under Moses, baptism is not a ceremonial cleansing. These were symbolic, they could not “make the worshiper perfect in conscience since they relate only to food and drink and various washings,” and were “regulations for the body.” (Hebrews 9:9-10) Baptism in the name of Jesus is an appeal to God for an internal cleansing in which we pledge to the Lord our commitment. The writer of Hebrews says that “our hearts [are] sprinkled to cleanse us from a guilty conscience and…our bodies [are] washed with pure water.” In baptism God sprinkles the blood of Jesus on our hearts, forgiving our sins, and cleansing our conscience from its guilt.