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.
Forgiveness
Forgiveness is central to Christian ethics and is a frequent topic in sermons and theological works. Considering Mark 11:25, and , that follows the Lord's Prayer, "For if you forgive men when they sin against you, your heavenly Father will also forgive you. But if you do not forgive men their sins, your Father will not forgive your sins.," Forgiveness is not an option to a Christian, rather one must forgive to be a Christian. Forgiveness in Christianity is a manifestation of submission to Christ and fellow believers.