The seared conscience is referred to in 1 Timothy 4:2 where Paul talks about those whose consciences—their moral consciousness—have been literally “cauterized” or rendered insensitive in the same way the hide of an animal scarred with a branding iron becomes numb to further pain. For human beings, having one’s conscience seared is a result of continual, unrepentant sinning. Eventually, sin dulls the sense of moral right or wrong, and the unrepentant sinner becomes numb to the warnings of the conscience that God has placed within each of us to guide us (Romans 2:15).
At the point of salvation, we are cleansed from the sin inherited from Adam and all personal sins. But as we continue in our Christian walk, we are still prone to sin. When we do, God has provided us with a bar of soap to restore us to the point of salvation. “If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness” (1 John 1:9). When we allow ourselves to practice mental attitude sins, we are quenching the Holy Spirit. We are commanded not to quench the Holy Spirit who indwells us (1Thessalonians 5:19). When we continue in our mental attitude sins without confessing and begin to practice these sins in our bodies (James 1:15), we grieve the Holy Spirit, which we are not to do (Ephesians 4:30). Once again, we have the choice to confess and repent or to continue in sin and backsliding. When we continue in sin, our souls begin to become morally callous. We finally come to a point where our conscience is seared and is unable to help us determine right from wrong. It is as if a hot iron was applied to our conscience and it is destroyed. Even worse, we don’t care how sinful we are. This is what is meant in 1Timothy 4:2, where Paul is referring to false teachers: “Such teachings come through hypocritical liars, whose consciences have been seared as with a hot iron.” You can easily see this with pure evil. A serial killer, for example, has had his conscience seared, and it no longer operates and guides him in what is right and what is wrong.
Christians who keep sinning despite divine discipline can actually sin themselves right out of this life and into God’s presence. God does this in order to keep such a one from doing any more damage to himself and to his witness for His Holy Name. “If anyone sees his brother commit a sin that does not lead to death, he should pray and God will give him life. I refer to those whose sin does not lead to death. There is a sin that leads to death. I am not saying that he should pray about that. All wrongdoing is sin, and there is sin that does not lead to death” (1 John 5:16-17). These sins do not cause us to lose our salvation, but they definitely affect our relationship with God and others. We are wise if we never deteriorate to the point of having our consciences seared.