Eternal sin
In Catholic teaching there are six sins that blaspheme against the Holy Spirit. They are: Several passages in the Bible are frequently interpreted as referring to the unforgivable sin:
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.