How would one know what is right and what is wrong? Is there a standard of measurement for morality? What would happen if each person does what seems to be right to him or her?
Allah has a standard of righteousness, which weighs, measures, and defines absolutely what is right and what is wrong. His standard is exact, fair, honest, and eternally constant. Based on His standard of righteousness, each person on this planet Earth will be judged. The person's whole life from birth to his last breath will be scrutinized. His thoughts, motives, actions, and speech will be weighed. As a result of Allah's judgment, each one will receive a grade: Pass or Fail.
It is through Allah's takqua that we become muttaqeen (righteous). As muttaqeen, we walk on Allah's Straight Path guided by His His sacred Books: the Noble Qur'an and the Holy Scriptures. Like Abraham (pbuh), we take God by His word and live by faith. Like David (pbuh), we fall yet repent and continue on our walk with God. It is only through God's power that we can overcome Satan's temptations. We solely depend upon God's takqua rather than our own goodness. Satan's counterfeit system of salvation is for us to earn it religiously through good deeds. This latter system, based on self-righteousness, seems to be right. But it is Satan's ploy of getting us to focus our attention on ourselves rather than on God and His righteousness.