Traditionalism (perennialism)
Traditionalism posits the existence of a perennial wisdom or perennial philosophy, primordial and universal truths which form the source for, and are shared by, all the major world religions.
René Guénon, Ananda Coomaraswamy and Frithjof Schuon.
The perennial philosophy, also referred to as perennialism and perennial wisdom, is a perspective in philosophy and spirituality that views religious traditions as sharing a single, metaphysical truth or origin from which all esoteric and exoteric knowledge and doctrine has grown.
One of two known editions of the title page of William Blake's "All Religions Are One". Publication date 1795. Blake accepted that all religions and philosophies in human history were one because they derived from the same single source.