
569 Just as in an earthly kingdom the worst crime is that of treason, as it cuts at the very existence of the State, so in the spiritual kingdom, the unforgivable sin is that of contumacious treason against Allah by putting up Allah's creatures in rivalry against Him. This is rebellion against the essence and source of spiritual Life. It is what Plato would call the "lie in the soul.." But even here, if the rebellion is through ignorance, and is followed by sincere repentance and amendment, Allah's Mercy is always open ( 4:17 ).

18 A person will never be forgiven if they die as a disbeliever. But if they repent before their death and mend their ways, then their repentance will be accepted (see 25:68-70).