Eternal sin
In Catholic teaching there are six sins that blaspheme against the Holy Spirit. They are: Several passages in the Bible are frequently interpreted as referring to the unforgivable sin:
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.