The conscience changed because of sin. It also changes according to environment, sensations, thoughts, and attitudes of others. Therefore the fluctuation of changes from one to another can make one person think that something is right is wrong and another person think that same thing is right.
The conscience is a thinking process that a person goes through to collect knowledge and identify the problem. But it is an untrustworthy source when it comes to making decisions because it is not the voice of God.
To insure that our conscience is pure, it must be led by the Holy Spirit.
God has given every person a conscience to guard and guide them. This is not the same as the Holy Spirit because the Holy Spirit only dwells in those who have believed in Jesus Christ for salvation. Once saved, the Spirit then works through the conscience to remind us that some attitudes, thoughts, words, and actions don’t fit our new identity in Christ. The more committed we are to Him, the louder our conscience will be.
1 Timothy 1:18-20 ESV This charge I entrust to you, Timothy, my child, in accordance with the prophecies previously made about you, that by them you may wage the good warfare, holding faith and a good conscience. By rejecting this, some have made shipwreck of their faith, among whom are Hymenaeus and Alexander, whom I have handed over to Satan that they may learn not to blaspheme.
This was a warning to Timothy, that we should heed, that spiritual "shipwreck" eventually comes to those who feel the conviction of their conscience and reject its signals. God gave us the conscience for our protection, but it's of no use if we ignore it and reject its counsel
How does the conscience work?
It judges a man’s soul in three areas—attitude, conduct, and behavior.
It’s like spiritual radar sending out signals that danger is near.
It's like a grid system that sends a stop signal whenever something wrong hits it.
The conscience is designed to protect us from temptations and sin, and we must be careful not to violate it by taking that first step in the wrong direction. At the first warning, we must make a choice to follow its direction, because we cannot violate our conscience and walk in God’s will or enjoy His blessings.
A good conscience is very sensitive and provides sound direction.
1 Timothy 1:19 ESV holding faith and a good conscience. By rejecting this, some have made shipwreck of their faith,
A struggling conscience is weak and may easily yield to temptation
1 Corinthians 8:7-12 ESV However, not all possess this knowledge. But some, through former association with idols, eat food as really offered to an idol, and their conscience, being weak, is defiled. Food will not commend us to God. We are no worse off if we do not eat, and no better off if we do. But take care that this right of yours does not somehow become a stumbling block to the weak. For if anyone sees you who have knowledge eating in an idol's temple, will he not be encouraged, if his conscience is weak, to eat food offered to idols? And so by your knowledge this weak person is destroyed, the brother for whom Christ died. Thus, sinning against your brothers and wounding their conscience when it is weak, you sin against Christ.
A soiled conscience. When we do what we know is wrong, our conscience becomes defiled by sin and cannot judge rightly.
Titus 1:15 ESV To the pure, all things are pure, but to the defiled and unbelieving, nothing is pure; but both their minds and their consciences are defiled.
A seared conscience. This is the worst state possible because the conscience has become so hardened that it no longer works. It’s the result of repeated disobedience to God. A seared conscience allows people to live a completely immoral lifestyle without feeling like it’s wrong.
1 Timothy 4:1-2 ESV Now the Spirit expressly says that in later times some will depart from the faith by devoting themselves to deceitful spirits and teachings of demons, through the insincerity of liars whose consciences are seared,
Romans 1:21, 23-25 ESV For although they knew God, they did not honor him as God or give thanks to him, but they became futile in their thinking, and their foolish hearts were darkened. and exchanged the glory of the immortal God for images resembling mortal man and birds and animals and creeping things. Therefore God gave them up in the lusts of their hearts to impurity, to the dishonoring of their bodies among themselves, because they exchanged the truth about God for a lie and worshiped and served the creature rather than the Creator, who is blessed forever! Amen.
The Holy Spirit not only rebukes and rejects the wrong act or the wrong desires but also corrects and encourages through the promises of God for redemption and salvation.
1 Corinthians 2:14-16 ESV The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned. The spiritual person judges all things, but is himself to be judged by no one. "For who has understood the mind of the Lord so as to instruct him?" But we have the mind of Christ.
The conscience is a trustworthy guide only when it is informed and ruled by God.
What makes something a sin is not just being out of alignment with our values but in choosing our own will over the will of God. So our conscience is only trustworthy when it does not lead us to choose our will over God’s will.
The conscience is an awesome thing that God put within us to help us live a holy and righteous life. It, along with the Holy Spirit, identifies whatever is wrong and should be avoided. Knowing that God loves us, is always working on our behalf, and has our best interests at heart should motivate us to listen and obey the promptings of our conscience. We may not always understand why the Lord is stopping us from going in a specific direction, but we can trust Him and His Word as the final authority for our lives because He is always right about every situation we encounter.
Proverbs 3:5-6 ES V Trust in the Lord with all your heart, and do not lean on your own understanding. In all your ways acknowledge him, and he will make straight your paths.