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 .
Excommunication
In the more grievous or recalcitrant cases, excommunication becomes a disciplinary option. Excommunication is generally reserved for what are seen as the most serious sins, including committing serious crimes such as murder, child abuse, and incest; committing adultery; involvement in or teaching of polygamy; involvement in homosexual conduct; apostasy; participation in an abortion; teaching false doctrine; or openly criticizing church leaders. A 2006 revision to the "Handbook" states that formally joining another church constitutes apostasy and is an excommunicable offense; however, merely attending another church does not constitute apostasy.