"[The study] shows that, under carefully controlled conditions, psilocybin can be administered safely and that it can occasion a mystical-type experience, which scientific measures say are very similar to spontaneously occurring mystical experiences" Griffiths said in an e-mail to ABC News. "The results suggest that such events may have lastingly beneficial consequences."
Other scientists familiar with hallucinogens and pharmaceuticals also praised the possible benefits of studying such chemicals.
"I was most impressed by the large percentage of individuals who reported a much more positive effect afterwards. That to me is very significant. They are thinking of taking this to cancer patients and difficult substance abusers," said James A. Smith, chairman of the Physiology and Pharmacology Department at Wake Forest University Baptist Medical Center.
The work is similar to the "Good Friday" experiment conducted in1962 by a minister and doctor said Rick Doblin, president of the Multidisciplinary Association for Psychedelic Studies. In that study, psilocybin also produced mystical experiences in most of the participants.
"This kind of work should be a top priority of our society. People have some of the most profound experiences of their lives after taking psilocybin. This mystical experience they talk about from the Good Friday experiment is something that tends to have people become more tolerant and compassionate," Doblin said. "We're talking about how psilocybin is a tool that helps people have these remarkable experiences."
Just because the active ingredient is illegal doesn't mean it should not be studied, noted Dr. Jeffrey Kahn, the director of the Center for Bioethics at University of Minnesota.
"If you step back and ask: Have we ever used illegal drugs in other medical research? There is probably a long list of drugs that started off illegal but had very useful purposes in medicine, such as marijuana," Kahn said. "This study seems less unusual now than in the 1960s since many more people take medications or drugs now compared to the 60s."
However, the study raises important safety questions, said Laurie Zoloth, a professor of Medical Ethics and Humanities at Northwestern University in Chicago.
"There is no known antagonist for this drug, unlike others -- if someone's peak moment turns out to be... being eaten by a terrifying sea creature, there is no way to rescue them from the thing we used to call 'a bad trip,'" Zoloth said. "The long-term side effects are not known."
She also wasn't that impressed by the drug's effects on mood.
"If such an experience meant that you suddenly became aware of injustice, poverty and inequality in the world, and became devoted to caring for the vulnerable in a selfless manner, I might be more impressed," she said.
Dr. Rosamond Rhodes, a professor of Medical Education at Mount Sinai School of Medicine and director of Bioethics Education, questioned some elements of the study's design. Not only was the study limited to people with religious backgrounds, but religious experiences could have been subtly or unduly promoted by the research administrators.