Quakers, or Friends, are members of a family of religious movements collectively known as the Religious Society of Friends. The central unifying doctrine of these movements is the priesthood of all believers. Many Friends view themselves as members of a Christian denomination. They include those with evangelical, holiness, liberal, and traditional conservative Quaker understandings of Christianity. Unlike many other groups that emerged within Christianity, the Religious Society of Friends has actively tried to avoid creeds and hierarchical structures.