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 .
Internal sin
Internal sin, in Christianity, is the idea that sin may be committed not only by outward deeds but also by the inner activity of the mind, quite apart from any external manifestation. Thought crimes were as old as heresy, but the Reformation's alarms received new emphasis at the Council of Trent (Session XIV, chapter. v). The session, while reiterating that all mortal sins must be confessed, singled out the unspoken ones that "sometimes more grievously wound the soul and are more dangerous than sins which are openly committed".