Eternal sin
However, the Church further believes there is no offence, however serious, that cannot be taken away by Baptism, or absolved from in the Confessional—that no one, however wicked and guilty, may not confidently hope for forgiveness. The Catechism says that Christ desires "the gates of forgiveness should always be open to anyone who turns away from sin." As did St Augustine, the Catholic Church today teaches that only dying unrepentant for one's sins is the only unforgivable sin. Indeed, in "Dominum et vivificantem" Pope John Paul II writes "According to such an exegesis, 'blasphemy' does not properly consist in offending against the Holy Spirit in words; it consists rather in the refusal to accept the salvation which God offers to man through the Holy Spirit, working through the power of the Cross", and "If Jesus says that blasphemy against the Holy Spirit cannot be forgiven either in this life or in the next, it is because this "non-forgiveness" is linked, as to its cause, to "non-repentance," in other words to the radical refusal to be converted. This means the refusal to come to the sources of Redemption, which nevertheless remain "always" open in the economy of salvation in which the mission of the Holy Spirit is accomplished."
Theology of Søren Kierkegaard
Sin is separation from God but despair over sin is separation again. Kierkegaard said, "The consciousness of sin definitely belongs to the consciousness of the forgiveness of sin." Why would someone sit and reflect on sin to such an extent that an eternal happiness is exchanged for an eternal unhappiness or even a temporal unhappiness? This reflection is done in time but the consequence of the reflection leads one to lose hope in the possibility of any good coming from oneself. Kierkegaard says Christianity invites the single individual to become a partaker not only of the consciousness of sin but also of the consciousness of forgiveness but we seem to concentrate on the former to a remarkable degree. He said the following in "Three Discourses on Imagined Occasions" (1845) and "Practice in Christianity" (1850):