For no human being will be justified in his sight by works of the law, since through the law comes knowledge of sin. But now the righteousness of God has been manifested apart from law, although the law and the prophets bear witness to it, the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction, since all have sinned and fall short of the glory of God, they are justified by his grace as a gift, through the redemption which is in Christ Jesus, whom God put forward as an expiation by his blood, to be received by faith.
Guilt is a universal experience.
Everybody at some time or other has had the bad feeling of not doing what he ought to have done. Even people who deny that there is any such thing as right and wrong are trapped by the law of God written on their hearts. They set out to prove there is no such thing as right and wrong and that all ethics are relative and arbitrary, but wind up saying it is right for you to agree with them and wrong for you not to. No one has ever successfully erased the sense of ought which God writes in every human soul. Our moral sensibilities may be perverted so that they are the very opposite of God's, but everyone senses that he ought to do certain things and not others.