Eternal sin
In Christian hamartiology, eternal sins, unforgivable sins, or unpardonable sins are sins which will not be forgiven by God. One eternal or unforgivable sin (blasphemy against the Holy Spirit) is specified in several passages of the Synoptic Gospels, including , , and .
Christianity
With around 2.4 billion adherents, split into three main branches of Catholic, Protestant and Eastern Orthodox, Christianity is the world's largest religion. The Christian share of the world's population has stood at around 33% for the last hundred years, which means that one in three persons on earth are Christians. This masks a major shift in the demographics of Christianity; large increases in the developing world have been accompanied by substantial declines in the developed world, mainly in Europe and North America. According to a 2015 Pew Research Center study, within the next four decades, Christians will remain the world's largest religion; and by 2050, the Christian population is expected to exceed 3 billion.