They are more likely to suffer from a range of mental health problems than either the conventionally religious or those who are agnostic or atheists, found researchers at University College London.
They are more disposed towards anxiety disorders, phobias and neuroses, have eating disorders and drug problems.
In addition, they are more likely than others to be taking medication for mental health problems.
Professor Michael King, from University College London, and his fellow researchers wrote in the British Journal of Psychiatry: "Our main finding is that people who had a spiritual understanding of life had worse mental health than those with an understanding that was neither religious nor spiritual.”
The study was based on a survey of 7 403 randomly selected men and women in England who were questioned about their spiritual and religious beliefs, and mental state.
Of the participants, 35% described themselves as "religious”, meaning they attended a church, mosque, synagogue or temple. Five in six of this group were Christian.
Almost half (46%) described themselves as neither religious nor spiritual, while the 19% remainder said they had spiritual beliefs but did not adhere to a particular religion.
Members of this final group were 77% more likely than the others to be dependent on drugs, 72% more likely to suffer from a phobia, and 50% more likely to have a generalised anxiety disorder.
They were also 40% more likely to be receiving treatment with psychotropic drugs and at a 37% higher risk of neurotic disorder.
The researchers concluded: "We conclude that there is increasing evidence that people who profess spiritual beliefs in the absence of a religious framework are more vulnerable to mental disorder.
"The nature of this association needs greater examination in qualitative and in prospective quantitative research.” - The Daily Telegraph