Eternal sin
Thomas Aquinas lists, or has responded to, six sins that supposedly go against the Holy Spirit:
Thomas Aquinas explains that the unforgivability of blasphemy against the Holy Spirit means that it removes the entrance to these means of salvation; however, it cannot hinder God in taking away this obstacle by way of a miracle.
Christian views on sin
Roman Catholic doctrine also sees sin as being twofold: Sin is, at once, any evil or immoral "action" which infracts God's law and the inevitable consequences, the "state of being" that comes about by committing the sinful action. Sin can and does alienate a person both from God and the community. Hence, the Catholic Church's insistence on reconciliation with both God and the Church itself.