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 .
Great Apostasy
In Christianity, the term Great Apostasy is derived from the Second Epistle to the Thessalonians, in which the Apostle Paul informs the Christians of Thessalonica that a great apostasy must occur before the return of Christ, when "the Man of Sin is revealed, the Son of Destruction" (chapter ). As no such thing had yet occurred, Paul says that Christ cannot have returned yet.