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
Other Christian scholars understand sin to be fundamentally relational—a loss of love for the Christian God and an elevation of self-love ("concupiscence", in this sense), as was later propounded by Augustine in his debate with the Pelagians. As with the legal definition of sin, this definition also affects the understanding of Christian grace and salvation, which are thus viewed in relational terms.