The question/claim: "Does Allah forgive every sin? On one side, 'Allah forgives all sins' (39:53); on the other, 'Allah does not forgive associating partners with Him' (4:48). Isn't that a contradiction?"
The two verses
"…Indeed, Allah forgives all sins. Indeed, He is the Forgiving, the Merciful." (39:53)
"Indeed, Allah does not forgive associating partners with Him (shirk), but forgives what is other than that for whom He wills." (4:48; the same in 4:116)
Contradiction, or a condition?
The two verses state the same condition from different sides: repentance / turning back.
- The verse right after 39:53 makes it explicit: "Turn to your Lord and submit to Him before the punishment comes." (39:54) So "forgives all sins" is for the servant who turns to Him.
- The shirk that 4:48 says is "not forgiven" is dying upon shirk without repentance. With repentance, even shirk is forgiven — the Qur'an says that for the one who believes and turns to Him, He "turns evil deeds into good" (25:70; 20:82). The door that closes is repentance deferred to the moment of death, or one dying in denial (4:18).
What if one repents of shirk? — The Qur'an's explicit answer
This is no assumption; the Qur'an says it explicitly about disbelief/shirk itself:
"Say to those who disbelieve: if they desist, what is past will be forgiven them." (8:38)
And right after 25:68-69 — which lists the gravest triad (shirk, unjust killing, adultery) and warns of everlasting punishment — comes the exception:
"Except those who repent, believe and do righteous deeds; for them Allah turns evil deeds into good ones." (25:70)
History confirms it: most of the first Muslim generation were former polytheists; on turning to tawḥīd their past was forgiven (they are precisely the addressees of 8:38).
So:
- With repentance: every sin — including shirk — can be forgiven (8:38; 39:53; 25:70; 42:25).
- Dying upon shirk without repentance: shirk is not forgiven (4:48).
An honest limit
- What is clear: despairing of God's mercy is forbidden (39:53), and the door of repentance is open until death comes (39:54; 4:18). For the one who repents, there is no "unforgivable sin" in the Qur'an.
- What is left to divine will: for sins below shirk, 4:48 says "for whom He wills" — this belongs to God's will; we cannot pass a final verdict ("saved" or "doomed") on any individual.
- Contested interpretation: the scope of "whom He wills" and the state of one who dies upon shirk are matters of theological debate; we give what the text says and leave the rest to God.
Conclusion: the apparent contradiction is a matter of condition, not a real contradiction: with repentance and turning back, Allah can forgive every sin; dying upon shirk without repentance is the exception. The two verses complete each other.
Source: Qur'anic verses (M. Okuyan meal). Presented with a text/interpretation distinction.