Eternal sin
In Christian hamartiology, eternal sins, unforgivable sins, or unpardonable sins are sins which will not be forgiven by God. One eternal or unforgivable sin (blasphemy against the Holy Spirit) is specified in several passages of the Synoptic Gospels, including , , and .
God in Islam
Tawhid constitutes the foremost article of the Muslim profession. The deification or worship of anyone or anything other than God (shirk) is the biggest sin in Islam. The entirety of the Islamic teaching rests on the principle of Tawhid.