With the notion of moral autonomy being widespread in our era, people often demand a rational explanation for why someone cannot “just be a good person” without faith and scriptural morality. Certainly, humanistic virtues such as compassion and justice are independently praiseworthy, partially inborn, and can invite God’s blessings in this life. However, in the grander scheme of salvific eligibility in the hereafter, accepting God’s message—upon discovering it—is necessary for validating one’s goodness before God. Being good is contingent upon one’s existence, good intentions, and the various faculties and resources (strength, wealth, etc.) by which a person enacts these intentions.

Since all these qualities and characteristics are endowed by God, rejecting God would render this good unrewardable in the afterlife, for it would then be—in essence—a plagiarized goodness. We as people rightfully view the most impressive research with awe and admiration, but that sentiment quickly transforms into disgust upon realizing it was actually the work of another whose contribution this fraudulent person deliberately hid. People do not just see plagiarism as disgraceful, but rather as condemnable.

Another reason why believing in the messengers is inseparable from being a good person is that only the messengers can thoroughly define good, through the inspiration they receive from God. Moral philosophers, for instance, have never been able to agree on how to apply the widely accepted principle of “do no harm” because of the complexity of varying contexts.

Even with the “golden rule” of treating others as you would like to be treated, though it is accepted by nearly everyone in theory, striking the perfect balance between competing virtues is not always easy in practice. Aristotle famously discussed this challenging need to find the “golden mean” between two poles of excess in moral behavior. History also attests that people— even with good intentions and advanced education—often live their lives with principles that are destructive and, like cancer, the damage caused can sometimes remain hidden until it is irreparable. Such people may have genuinely sought “being good,” and “not hurting anyone,” while oblivious to the evil and hardship their ideas inflicted against themselves and society.

In a word, the “do no harm” rule always risks being sacrificed at the altar of subjective morality. For this reason, God sent His final messenger صلى الله عليه وسلم to fully define goodness, protecting humanity against shortsightedness, the desensitization we all experience from social conditioning, and the perversions of our perceptions that often follow. Allah says, And know that among you is the Messenger of Allah. If he were to obey you in much of the matter, you would be in difficulty, but Allah has endeared to you the faith and has made it pleasing in your hearts and has made hateful to you disbelief, defiance, and disobedience. Those are the [rightly] guided.21

Tawḥīd (pure monotheism), which is to single God out in everything unique to Him, is the ultimate supreme good, and this would also be impossible without the messengers. Humanity cannot know God, nor know His beauty and grandeur, nor know the path to His pleasure, nor know His promises and threats, nor embody His prescriptive will which He lovingly ordained for the betterment of His creation, without the prophets and messengers. Consider the dismal state of the world before God sent Noah ,22 or the darkness that smothered humanity after Jesus Christ  and shortly before the advent of Prophet Muhammad صلى الله عليه وسلم, to understand humanity’s moral need for prophethood at every junction of human history.