sins against the Holy Spirit
Sins that embody a stubborn resistance to the inspirations of the Holy Spirit and an open contempt for his gifts.
Although no sin is absolutely unpardonable, those who sin against the Holy Ghost stubbornly resist the influence of grace and do not wish to repent.
Hence their sin cannot be forgiven them.
- despair of one's salvation
- presumption of God's mercy
- impugning the known truths of faith
- envy of another's spiritual good
- obstinacy in sin
- final impenitence
New Catholic Dictionary