Eternal sins or unforgivable sins or unpardonable sins are part of Christian hamartiology, which is the Christian theology of sins. These are sins which will not be forgiven by God whereby salvation becomes impossible. One eternal or unforgivable sin is specified in several passages of the Synoptic Gospels: verse 29 in Mark 3 states that there is one sin considered eternal and that is "blasphemy against the Holy Spirit".