Complex sentence: Eternal sins or unforgivable sins or unpardonable sins are part of the Christian theology of sins or Hamartia and are sins which cannot or will not be forgiven whereby salvation becomes impossible.
Split into simpler sentences: Eternal sins or unforgivable sins or unpardonable sins are part of Harmatia which is the Christian theology of sins. These are sins which cannot or will not be forgiven whereby salvation becomes impossible.