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 .
Tawhid
Greater Shirk consists of the above-mentioned deeds. A person commits lesser shirk (Shirk-al-Asghar) or hidden polytheism when he claims to believe in God but his thoughts and actions do not reflect his belief. There are also minor forms of Shirk, they must be avoided as well; these include committing a good deed to show off, making an oath in the name of anyone except God. Within Islam, shirk is an unforgivable crime; God may forgive any sin if one dies in that state except for committing shirk, repentance is required for its forgiveness.