According to the Quran, what sin can never be forgiven, and why?

 In the Quran, there are specific sins that are considered grave and for which forgiveness is challenging. Let’s explore these:

1. Shirk (Associating Partners with Allah):

   • The sin of shirk, which involves associating partners with Allah, is considered unforgivable.
   • Allah explicitly states: “{Verily, Allah forgives not that partners should be set up with Him in worship…}” (Quran 4:48).
   • Shirk undermines the fundamental principle of monotheism and the oneness of Allah.

2. Deliberate Killing of a Believer:

   • Intentionally killing a fellow Muslim without a valid reason is another grave sin.
   • Allah says: “{And whoever kills a believer intentionally, his recompense is Hell to abide therein, and the Wrath and the Curse of Allah are upon him, and a great punishment is prepared for him.}” (Quran 4:93).
   • However, some scholars believe that if the killer sincerely repents, Allah may forgive even this sin.

3. Dying in a State of Disbelief (Kufr):

   • If a person dies without accepting Islam (i.e., remains a disbeliever), their sins are not forgiven.
   • Allah’s mercy extends to those who repent, but dying in a state of disbelief is an exception.

4. Other Sins and Repentance:

   • For all other sins, Allah’s forgiveness is available through sincere repentance.
   • Repentance wipes out every sin, without exception.
   • The Prophet Muhammad (peace be upon him) said: “Every sin is forgiven except a person who deliberately kills a Muslim or a person who dies as a non-Muslim (disbeliever).” [Abu Daawood]

In summary, while Allah’s mercy is vast, certain sins—such as shirk, deliberate killing of a believer, and dying in disbelief—have severe consequences. Repentance remains the key to seeking forgiveness, and Allah’s judgment is just and merciful¹².