Zoroastrianism can be conceived as a devotional monotheism, although not a pure or radical one, because it includes an interweaving of a dualism between good and evil with polytheism, a situation that can give one the impression that it is contradictory. Zoroastrians also believe that the cadaver of a righteous person is even more susceptible to impurity than that of an evil person because the latter type of person is already corrupted by evil forces. Similar to other patriarchal religious cultures, women were expected to embrace the role of motherhood for the good of the religion. The distinction between purity and pollution is based on a basic cosmic and ethical dualism between righteousness and evil that is often called the "lie". Fire and water play important roles in the dichotomy between purity and pollution and in Zoroastrian eschatology. During the nineteenth century, the Zoroastrian community in India was challenged by Christianity, introduced by the colonial powers.