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.
Sin
In a religious context, sin is an act of transgression against divine law. In Islamic ethics, Muslims see sin as anything that goes against the commands of Allah (God). Judaism regards the violation of any of the 613 commandments as a sin.