Conscience is a spiritual quality that bids man good attitude and thought, and helps him think straight and tell right from wrong.
One of the important aspects of conscience is that it is common to all people. In other words, what feels right to the conscience of a man also feels right to the conscience of all others provided that the same conditions prevail. The conscience of one man never falls out with that of another. The reason lies in the source of conscience: it is the inspiration of Allah. Through the conscience, Allah lets us know the best and the most beautiful behaviour and manners which it will please Him for us to adopt.
That conscience is an inspiration from Allah is mentioned in the Qur'an, in Surat ash-Shams:
And the self and what proportioned it and inspired it with depravity or taqwa, he who purifies it has succeeded, he who covers it up has failed. (Surat ash-Shams: 7-10)
In the above verses, Allah declares that He has inspired the self with depravity (to act in a sinful manner, to disobey, to deviate, to lie, to turn away from righteousness, to stir up trouble, to decline in good manners). The opposite is taqwa (awe or fear of Allah which inspires a person to be on guard against wrong action and eager for actions which please Him). It is this very conscience that makes man guard against evil deeds and find the right way.
One of the most important aspects of conscience is that it helps man to find what is right of his own accord. This will be discussed in more detail in forthcoming chapters. Conscience will surely show man what is right, even if nobody else will. However, what matters for man is to take recourse to his own conscience, listen to what it says, and act upon it. For this reason, we can say that conscience is the main component of religion.
Above all, there is one point that must be borne in mind; every man, from the moment of gaining consciousness, is responsible for what Allah inspires him with and what his conscience tells him. From the moment he starts to conceive the events around him and becomes able to judge for himself, he is expected to possess and be able to exercise the ability to hear and distinguish the voice of his conscience, and to have the will to follow it. From this point forward, he will be questioned about the actions he takes in the course of his life. If he follows his conscience, he will be rewarded with an eternal life in Allah's heaven, but if he follows his self, he will meet an eternal sealed vault of fire.