Quakers, also called Friends, belong to a historically Christian (Protestant) set of denominations known formally as the Religious Society of Friends. Members of the various Quaker movements are generally united by a belief in the ability of each human being to experience and access the light within or to see "that of God in every one". Some profess the priesthood of all believers, a doctrine derived from the First Epistle of Peter. They include those with evangelical, holiness, liberal, and traditional Quaker understandings of Christianity. There are also Nontheist Quakers whose spiritual practice is not reliant on the existence of God. To differing extents, the movements making up the Religious Society of Friends/Friends avoid creeds and hierarchical structures. In 2007, there were about 359,000 adult Quakers worldwide. In 2017, there were 377,557 adult Quakers, 49 per cent of them being in Africa.
