The bible refers to our Conscience several times. Paul refers to it in Romans. It is something we can destroy, just as we can destroy our bodies.
"Even when Gentiles, who do not have God's written law, instinctively follow what the law says, they show that in their hearts they know right from wrong. They demonstrate that God's law is written within them, for their own consciences either accuse them or tell them they are doing what is right." Romans 2:14-15
Conscience is not an instinct, it is a knowledge, a consciousness put within us by God, it is one of the things that differentiates us from animals. Though the conscience cannot act, it can and does judge. It takes our thoughts, words, deeds and motives and compares them with the moral law of God, with the will of God. Then it passes its judgment.
The Bible is teaching that everyone, even if they've never heard about God's Word, knows they should act according to God's morality by nature. The 18th-century German Philosopher Immanuel Kant said, "Two things fill the mind with ever increasing wonder and awe, the more often and the more intensely the mind of thought is drawn to them--the starry heavens above me and the moral law within me." (Immanuel Kant, Critique of Pure Reason, 1781).
There is a "law" or a "morality" operating in everyone's own heart either accusing us or telling us we are doing what is right. Because of this, we are responsible to do what is right and to avoid what is wrong or sinful, and when we violate our conscience, we feel guilt.
Problem is that our spiritual standard is very far from God's standard, moral, ethic and Conscience.
It seems that people created their own standard, moral, ethic and Conscience, so we don't have any more absolute valuers (from God) but relative, changeable values, and this is the problem in today's society.
Everybody replace God with self proclaimed ''freedom'' and human rights and this create chaos and confusion in society.
Without God there is no ideal world with absolute values to guide us.