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.
LGBT clergy in Christianity
The Presbyterian Church in America (PCA), the second-largest Presbyterian denomination in the United States, adheres to what they perceive as the biblical stance on homosexuality, affirming that "the act of homosexuality is a sin according to God's Word." Therefore, a practicing homosexual continuing in this sin would not be a fit candidate for ordination or membership in the Presbyterian Church in America.