The religion is only about 150 years old.
: This is a highly disparate group and not a single religion.
Mary Evelyn Tucker, Visiting Scholar at the Graduate Theological Union, teaches courses in world religions, Asian religions, and religion and ecology. She received her Ph.D. from Columbia University in the history of religions, specializing in Confucianism in Japan. She has published Moral and Spiritual Cultivation in Japanese Neo-Confucianism (Albany, N.Y.: SUNY, 1989). She co-edited with John Grim, Worldviews and Ecology (Maryknoll, N.Y.: Orbis, 1994), with Duncan Williams, Buddhism and Ecology (Cambridge, Mass.: Harvard/CSWR, 1997), with John Berthrong, Confucianism and Ecology (Harvard/CSWR, 1998), and, with Christopher Chapple, Hinduism and Ecology (Harvard University Press/CSWR, 2000). She and John Grim are editors for the Orbis series on Ecology and Justice.
Obviously this is broad classification, not a single religion.
On the other hand, some Hindu writers are so inclusive that they claim as Hindus adherents of any religion that arose in a Hindu environment, including Buddhists, Jains and Sikhs.
This Essay Is Confucianism a Religion
The boundaries between Spiritism and other categories, especially Christianity (especially Catholic and Baptist), Yoruba religion and primal-indigenous religions, can be quite uncertain.
Essay about Confucianism, Daoism & Legalism - …
But a worldwide number which eliminated adherents who are primarily Yoruba religionists more so than Spiritists would be smaller, and more in line with the Encyclopedia Britannica estimate.
Essay about Confucianism, Daoism & Legalism
Although "Santeria" is commonly used in comparative religion/academic literature, and it is becoming increasingly accepted among practitioners of the Western Yoruba/Orisha religious tradition, it is a term imposed by outsiders and its etymological roots have meaning that many in the tradition find offensive or at least inaccurate.