The Quran

أَم يَقولونَ افتَراهُ ۚ بَل هُوَ الحَقُّ مِن رَبِّكَ لِتُنذِرَ قَومًا ما أَتاهُم مِن نَذيرٍ مِن قَبلِكَ لَعَلَّهُم يَهتَدونَ

Ali Unal

Or do they say: he (Muhammad) has fabricated it? No, rather, it is the truth from your Lord, that you may warn a people to whom no warner has come before you (during a long interlude during which no Messengers appeared), so that they may be guided (to find and follow the Straight Path).¹

Deducing from We would never punish (a person or community for the wrong they have done) until We have sent a Messenger (to give counsel and warning) (17: 15), some Muslim scholars hold that one who has not heard the Name of God or the teachings of Islam will be “excused,” unless he or she is a wrongdoing, unjust person. God, as He wills, rewards such people for the good they have done, and they enjoy the blessings of Paradise.
There are other scholars, however, who are of the opinion that humankind is created with a capacity to find the Creator through the use of reason, even though we may not know His Names or Attributes, for we can also find Him in our conscience. A Bedouin once came to the Prophet and explained how he had attained faith: “Camel droppings point to the existence of a camel. Footprints on the sand tell of a traveler. The heaven with its stars, the earth with its mountains and valleys, and the sea with its waves – do they not point to the Maker, All-Powerful, Knowing, Wise, and Caring?” As he had attained faith in God through logical deduction, we cannot underrate the role of reason and thinking in faith. Thus, the exemption from punishment stated in 17: 15 means that unless a Messenger has been sent, no one will be held responsible for neglecting the other pillars of faith and for not living a life according to Islam, the complete submission to God. God uses Messengers to convey His injunctions, distinguishing what is good and evil, and does not leave human beings to stray into error because of fallible human judgment and experience.