Psychoactive plants that induce a form of altered states of consciousness (hallucinogen-induced ASC (H-ASC)) have been widely used during the religious rituals of many cultures throughout the centuries. Some of the psychoactive ingredients of the plants that were used during these religious rituals were opium, cannabis (tetrahydrocannabinol), psilocybin, mescaline, ibogaine, dimethyltryptamine, Peganum harmala, bufotenin, muscimol, thujone, ephedra, mandragora, Salvia divinorum, etc. The main purposes of these plants were spiritual healing; to contact with spirits; to contact with the souls of ancestors; to reach enlightenment (Nirvana or Satori); to become a master shaman, pagan, or witch; and to reach so-called-other realities. In most of the ancient religious rituals such plants were consumed as a part of the traditional shamanic or pagan culture for many centuries and most of the religious figures and images in the ancient and modern religious systems are a result of these hallucinogenic substances and H-ASC mind states. In the limbic system there can be a splendid source of archaic information and a religious symbolic and thought pool, which may have surfaced during the influence of psychoactive plants in the old shamanic religious rituals. This shamanic archaic information may have been important for the evolution and existence of the Homo sapiens species once upon a time. Thus, the entoptic images, phosphenes, mythological figures, such as demons, spirits, gods, goddesses, angels, supranatural creatures, mythical creatures (such as Pan, satyrs, nymphs, dragons, trolls, etc.) in folk tales, or the figures and characters of the modern institutionalized religions (such as angels, Satan, Jinns, many other religious thoughts, ideas and figures, etc.), most probably had been envisioned under the influence of these psychoactive plants during those religious ceremonies and rituals. Therefore, many ancient polytheistic pagan religious figures and/or some of the modern monotheistic religious characters, figures, or images may have close relationships with the ASCs experienced during psychoactive plant ingestions since the dawn of H. sapiens. As a further step, some of the figures and characters of modern contemporary religions, as well as old religions, might have been experienced in and derived from very ancient religious–psychedelic rituals, where different kinds of psychoactive plants had been used. Psychoactive plants are widespread and have been used by many cultures on the globe for centuries; they induce a kind of unusual, unexpected consciousness perception in human beings. Some of the psychoactive plants, which are banned today by industrialized societies, were cannabis, opium, psilocybin (magic mushrooms), ibogaine, DMT-containing plants, P. harmala, harmine–harmaline-containing plants, bufotenin (toad toxin), muscimol (magic mushroom), thujone (A. absinthium), ephedra, mandragora, S. divinorum, etc. Psychoactive plants might also be capable of unraveling archaic information and the subconsciousness. The chemicals in psychoactive plants may change human perception profoundly. Most of the figures, characters, and myths in the old or new religions might have been created under the influence of altered states during religious rituals using psychoactive plants.