Volunteer subjects reported conversing with God, experiencing ''ultimate transcendence'' and being suspended in a ''tactile field of light.''

According to the study, conducted by researchers from Johns Hopkins University and the Council on Spiritual Practices, subjects who took doses of psilocybin, a drug found in hallucinogenic mushrooms, reported sustained spiritual and religious benefits 14 months after ingestion.

Sixty-seven percent of participants rated the experience as one of the five most spiritually significant events in their lives, while 64 percent said it had increased their well-being or life satisfaction.

The 36 volunteers had no previous exposure to hallucinogens, and all identified themselves as regularly engaging in religious or spiritual activities.

Participants came from a mix of predominantly Christian backgrounds. Researchers said the results showed no correlation between an individual's denomination and the drug's spiritual effects.

The report is a follow-up to the group's 2006 study in which volunteers were given a single dose of psilocybin once during a two-month period and asked to rate their experience in a series of questionnaires.

Roland Griffiths of Johns Hopkins School of Medicine, who led the study, said researchers are ''just scratching the surface'' of the relationship between spirituality and science. Griffiths cautioned that psilocybin is not tantamount to ''God in a pill.''

''There are some people who say this is the meaning of spirituality or God, and it's not,'' Griffiths said. ''These kinds of observations cannot address the ultimate existential question of the existence of God or the existence of a higher power.''

Psilocybin has been used for centuries by indigenous cultures in North and South America but is illegal in the United States. The federal government classifies the drug as a Schedule 1 substance with no medical value. In recent years, research has been conducted to determine whether doses of psilocybin may have beneficial effects for patients with terminal illnesses or severe addictions.

''There are dangers even in a supervised setting,'' warned David Murray, chief scientist for the White House Office of National Drug Control Policy. Murray compared taking psilocybin to playing Russian roulette, saying it can cause fear, joy, elation or weeping, depending on the subject's mental state.

''You never know what you're going to get,'' Murray said. ''It's dangerous.''

Some proponents of the drug argue that psilocybin and other psychoactive substances used in religious ceremonies - known as entheogens - produce chemical changes no different from severe illness or prolonged fasting, which have been known to produce spiritual awakenings.

The Rev. Ken Barnes, a California United Church of Christ pastor and former director of the Council on Spiritual Practices, said bans on psychoactive drugs are part of a larger problem.

''I believe that in our secular society, we've moved away from primary religious experiences,'' said Barnes. ''Entheogens can introduce the spirit in a very dramatic way. I see them mainly as inductors into the spiritual world.''

Barnes expressed optimism that psilocybin would someday follow the same path to legalization as peyote, a hallucinogen found in cactus which was legalized for religious use in 1994.