All Religions are One is a series of philosophical aphorisms by William Blake, written in 1788. Following on from his initial experiments with relief etching in the non-textual The Approach of Doom (1787), All Religions are One and There is No Natural Religion represent Blake's first successful attempt to combine image and text via relief etching, and are thus the earliest of his illuminated manuscripts. As such, they serve as a significant milestone in Blake's career; as Peter Ackroyd points out, "his newly invented form now changed the nature of his expression. It had enlarged his range; with relief etching, the words inscribed like those of God upon the tables of law, Blake could acquire a new role."

In 1822, Blake completed a short two-page dramatic piece which would prove to be the last of his illuminated manuscripts, entitled The Ghost of Abel A Revelation in the Visions of Jehovah Seen by William Blake. Inscribed in the colophon of this text is "W Blakes Original Stereotype was 1788". It is almost universally agreed amongst Blakean scholars, that the "Original Stereotype" to which he here refers was All Religions are One and/or There is No Natural Religion.

During the 1770s, Blake had come to feel that one of the major problems with reproducing artwork in print was the division of labour by which it was achieved; one person would create a design (the artist), another would engrave it (the engraver), another print it (the printer) and another publish it (the publisher). It was unusual for artists to engrave their own designs, due primarily to the social status attached to each job; engraving was not seen as an especially exalted profession, and was instead regarded as nothing more than mechanical reproduction. Artists like James Barry and John Hamilton Mortimer were the exceptions to the norm insofar as they tended to engrave their own material. A further division in the process was that text and images were handled by different artisans; text was printed by means of a movable letterpress, whereas images were engraved, two very different jobs.

During Blake's training as a professional copy engraver with James Basire during the 1770s, the most common method of engraving was stippling, which was thought to give a more accurate impression of the original picture than the previously dominant method, line engraving. Etching was also commonly used for layering in such aspects as landscape and background. All traditional methods of engraving and etching were intaglio, which meant that the design's outline was traced with a needle through an acid-resistant 'ground' which had been poured over the copperplate. The plate was then covered with acid, and the engraver went over the incised lines with a burin to allow the acid to bite into the furrows and eat into the copper itself. The acid would then be poured off, leaving the design incised on the plate. The engraver would then engrave the plate's entire surface with a web of crosshatched lines, before pouring the ink onto the plate and transferring it to the printing press.

Frustrated with this method, Blake seems to have begun thinking about a new method of publishing at least as early as 1784, as in that year a rough description of what would become relief etching appears in his unpublished satire, An Island in the Moon. Around the same time, George Cumberland had been experimenting with a method to allow him to reproduce handwriting via an etched plate, and Blake incorporated Cumberland's method into his own relief etching; treating the text as handwritten script rather than mechanical letterpress, and thus allowing him to make it a component of the image.

Blake's great innovation in relief etching was to print from the relief, or raised, parts of the plate rather than the intaglio, or incised, parts. Whereas intaglio methods worked by creating furrows into which the acid was poured to create 'holes' in the plate and the ink then poured over the entire surface, Blake wrote and drew directly onto the plate with an acid-resistant material known as a stop-out. He would then embed the plate's edges in strips of wax to create a self-contained tray and pour the acid about a quarter of an inch deep, thus causing the exposed parts of the plate to melt away, and the design and/or text to remain slightly above the rest of the plate, i.e. in relief, like a modern rubber stamp. The acid was then poured off, the wax was removed, and the raised part of the plate was covered with ink before finally being pressed onto the paper in the printing press. This method allowed expressive effects which were impossible to achieve via intaglio. The major disadvantage was that text had to be written backwards as whatever was on the plate would print in reverse when pressed onto the paper. The dominant theory as to how Blake solved this problem is simply that he wrote in reverse. Another theory, suggested by David Bindman, is that Blake wrote his (acid-resistant) text on a sheet of paper the correct way around, and then pressed the paper onto the plate, thus reversing the text and producing the same result as if had he written it backwards in the first place.

Blake could also colour the plates themselves in coloured inks before pressing them or tint them with watercolours after printing. Because of this aspect, a major component of relief etching was that every page of every book was a unique piece of art; no two copies of any page in Blake's entire oeuvre are identical. Variations in the actual print, different colouring choices, repainted plates, accidents during the acid bath etc., all led to multiple examples of the same plate.

Blake himself referred to relief etching as "printing in the infernal method, by means of corrosives [...] melting apparent surfaces away, and displaying the infinite which was hid." A contemporary description of the method was provided by Blake's friend, J.T. Smith; "writing his poetry, and drawing his marginal subjects of embellishments in outline upon the copper-plate with an impervious liquid, and then eating the plain parts or lights away with aquafortis considerably below them so that the outlines were left as Stereotype."