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."
Mortal sin
A mortal sin (), in Catholic theology, is a gravely sinful act, which can lead to damnation if a person does not repent of the sin before death. A sin is considered to be "mortal" when its quality is such that it leads to a separation of that person from God's saving grace. This type of sin should be distinguished from a venial sin that simply leads to a weakening of a person's relationship with God. Despite its gravity, a person can repent of having committed a mortal sin. Such repentance is the primary requisite for forgiveness and absolution. Teaching on absolution from serious sins has varied somewhat throughout history. The current Catholic teaching was formalized at the 16th century Council of Trent.