The Qur'an Is The Criterion That Discriminates Between Right And Wrong

As guidance for humanity, and He has sent down the Furqan (the Standard by which to discern the true from the false). Those who reject Allah's Signs will have a terrible punishment. Allah is Almighty, Exactor of Revenge. (Surah Al 'Imran: 4) 

In the Qur'an, Allah admonishes people and shows them the true path. The Qur'an is the sole resource that leads people to the correct knowledge of Allah, the values of Islam, how to live in a way that pleases Allah, and an absolute criterion that distinguishes right from wrong. For this reason, one of the Qur'an's names is "Furqan": one that discriminates right from wrong.

In this world, people have their own beliefs, goals, values, thoughts, and outlook on life. However, the judgments that Allah proclaims in the Qur'an are the only values that can be considered just and right. As Allah states in the Surat al-Baqara: 120: "Allah's guidance is true guidance." Therefore, the goals and ways devised by people to realize their own interests can never lead them to the truth and salvation. The purpose of humanity's existence and how to attain it, the ideal morality and good conduct that must be shown throughout one's life, how to lead a physically and spiritually healthy life, the moment of death and what will happen to one's soul on the Day of Judgment - all of these are related in the Qur'an.

A person must read the Qur'an carefully in order to benefit from it and be rightly guided:

Those to whom We have given the Book, who recite it in the way it should be recited, such people believe in it. As for those who reject it, they are the losers. (Surat al-Baqara: 121) 

Reading the Qur'an as it should be read becomes possible when people have love and fear of Allah and adhere to it. Those who read the Qur'an in this way submit themselves to every judgment in the Qur'an and commit themselves fully to the meticulous observation of every verse.

Given this, those who adhere to it base all of their decisions upon light of the Qur'an and the Sunna of our Prophet (saas). Thanks to this attribute, believers can discriminate between right and wrong and make the best decision. As the verse: "Right guidance has become clearly distinct from error" (Surat al-Baqara: 256)
 
also makes clear, people of faith do not attempt to find a middle way between the Qur'anic values and the life of ignorance; rather, they are committed fully and assuredly to the Qur'an, which is the straightest path. Allah commands believers to hold fast to the Qur'an, as follows:

So hold fast to what has been revealed to you. You are on a straight path. It is certainly a reminder to you and to your people, and you will be questioned. (Surat az -Zukhruf: 43-44)

Those who distance themselves from Allah's revelations and insist upon disbelief have chosen trouble and torment both in this world and the next, for the type of life that Allah commands us to live is the one that most suits human nature. Therefore, people who do not comply with the Qur'an can never attain true peace and happiness, for they have abandoned a lifestyle that agrees with their very nature. To attain salvation and bliss both in this world and the next, people need to learn the true religion, the commands of our Lord, and comply meticulously with the Qur'an. Indeed, Allah warns people thus:

Do they then seek the judgment of the Time of Ignorance? Who could be better at giving judgment than Allah for people with certainty? (Surat al-Ma'ida: 50) 

Is it not enough for them that We have sent down to you the Book that is recited to them? There is certainly a mercy and reminder in that for people who believe. (Surat al- 'Ankabut: 51) 

The diagnosis, comments, reasoning, and recommendations of people who abide by the Qur'an and their ability to find solutions to the problems they face stem directly from the Qur'an. For this reason, they are always right, just, and wise.

The state of those who fail to comply with the Qur'an is stated as follows:

Is it other than the religion of Allah that you desire, when everything in the heavens and Earth, willingly or unwillingly, submits to Him and to Him you will be returned? (Surah Al 'Imran: 83) 

If anyone desires anything other than Islam as a religion, it will not be accepted from him, and in the Hereafter he will be among the losers. (Surah Al 'Imran: 85) 

The religion with Allah is Islam. Those given the Book only differed after knowledge had come to them, envying one another. As for those who reject Allah's Signs, Allah is swift at reckoning. (Surah Al 'Imran: 19)

For these reasons, people must abandon all fallacious beliefs and take only the Qur'an and the Sunna of our Prophet (saas) as an example. Otherwise, they will be overwhelmed by grief and great regret in the Hereafter and receive a severe punishment.