From Psychology Today:
Psychedelic drugs, including LSD, psilocybin, and mescaline, have long had an association withspiritual pursuits. For example, psychedelic plants, such as psilocybe mushrooms, peyote, and ayahuasca have long been used in shamanic traditions in the Americas (Lerner & Lyvers, 2006). Recent research has found that administering psychedelic drugs in a supportive setting can occasion profound mystical experiences. For example, a recent study found that about 60% volunteers in an experiment on the effects of psilocybin, who had never before used psychedelic drugs, had a “complete mystical experience” characterised by experiences such as unity with all things, transcendence of time and space, a sense of insight into the ultimate nature of reality, and feelings of ineffability, awe, and profound positive emotions such as joy, peace, and love (Griffiths, Richards, McCann, & Jesse, 2006).
Due to the association between psychedelic drugs and mystical experiences, some recent research has looked at how the spiritual belief and attitudes of psychedelic drug users compare to users of non-psychedelic drugs and to non-drug users. A study by Lerner and Lyvers (2006) compared people who used high doses of classic psychedelic drugs (e.g. LSD, mescaline and psilocybin) with people who used other illegal drugs (mostly marijuana and amphetamines) who had never tried psychedelic drugs, and people who had never used illegal drugs. (Only high-dose psychedelic drug users were included, as high doses are required to induce mystical states. Low dose usage is popular with people who primarily enjoy the perceptual effects such as enhancement of music during raves.) Psychedelic drug users endorsed more mystical beliefs (such as in a universal soul, no fear of death, unity of all things, existence of a transcendent reality, and oneness with God, nature and the universe). Psychedelic drug users also said they placed greater value on spirituality and concern for others, and less value on financial prosperity, than the other two groups. This accords with findings from another study (Móró, Simon, Bárd, & Rácz, 2011) that found that psychedelic drug users regarded spirituality as more personally important compared to users of other drugs and non-drug users. Spirituality in this latter study was defined as “one’s relationship to God, or whatever you perceive to be Ultimate Transcendence.”
These findings do suggest that people who use psychedelic drugs consider themselves more spiritual, and perhaps less materialistic, than people who prefer other drugs or who do not use illegal drugs at all. A more difficult question to answer is whether taking psychedelic drugs induces people to become more open to spiritual beliefs and values, or whether people who already have these beliefs and values are more inclined than others to use these drugs. Lerner and Lyvers suggest that the answer is probably a combination of both as persons on a spiritual quest are more likely to take these drugs and their subsequent experiences may strengthen and deepen their spiritual values and beliefs.
There does seem to be evidence that there may be a two-way relationship between psychedelic drug use and having spiritual and mystical beliefs. A study on psilocybin by Griffiths et al. (2011) found that people who had never used psychedelic drugs before reported long-term (assessed over a period of 14 months) increases in “death transcendence”. That is, participants expressed an increased belief that there is continuity after death, e.g. belief that death is not an ending but a transition to something even greater than this life. One of the core features of mystical experience is “an intuitive belief that the experience is a source of objective truth about the nature of reality” (MacLean, Johnson, & Griffiths, 2011). As noted earlier, about 60% of volunteers in the Griffiths et al. study reported a complete mystical experience, which they regarded as having sustained personal meaning and spiritual significance months later. From this it seems reasonable to think that one of the outcomes of the mystical experience was to convince volunteers that consciousness does continue after death. Additionally, as noted in a previous post, volunteers who experienced a complete mystical experience on psilocybin had a subsequent increase in the personalitydomain of openness to experience. People high in openness to experience also tend to endorse more mystical and spiritual beliefs, although they may also endorse less conventional religious belief.