Although Gardner criticised monotheism, citing the Problem of Evil, explicitly monotheistic forms of Wicca developed in the 1960s, when the U.S.-based Church of Wicca developed a theology rooted in the worship of what they described as "one deity, without gender". In the 1970s, Dianic Wiccan groups developed which were devoted to a singular, monotheistic Goddess; this approach was often criticised by members of British Traditional Wiccan groups, who lambasted such Goddess monotheism as an inverted imitation of Christian theology. As in other forms of Wicca, some Goddess monotheists have expressed the view that the Goddess is not an entity with a literal existence, but rather a Jungian archetype.