Results of a controversial US study addressing two of the most debated questions on "ex-gays" will be announced this week in Nashville.

First: "Is change of sexual orientation possible?" And second: "Is the attempt to change harmful?"

Researchers Stanton L. Jones of Wheaton College and Mark A. Yarhouse of Regent University, both of whom are evangelical Christians, conducted "A Longitudinal Study of Religiously Mediated Change in Sexual Orientation," asking the two questions which have been long debated by mental health professionals and Christian counsellors.

"We are evangelical Christians committed to the truth-seeking activity of science," Jones and Yarhouse said in a joint statement, addressing skeptics of Christian researchers on a matter of science. "In conducting and reporting this study, we took seriously the words of one of our heroes, C. S. Lewis, who said that science produced by Christian persons would have to be 'perfectly honest. Science twisted in the interests of apologetics would be sin and folly.'"

Many professional organisations, including the American Psychiatric Association and the American Medical Association, are critical of what some call "reparative" or conversion therapies. The American Psychological Association is currently revising its 10-year-old policy on counseling homosexuals after years of pressure from pro-gay groups that say such therapy is harmful. Evangelicals meanwhile are calling psychologists to respect religious commitments and allow those who are seeking change out of same-sex desires to be offered the help.

"For many years, mental-health professionals have taken the view that since homosexuality is not a mental disorder, any attempt to change sexual orientation is unwise," said prominent psychiatrist Dr. Robert Spitzer, according to the Los Angeles Times. "But for healthcare professionals to tell someone they don't have the right to make an effort to bring their actions into harmony with their values is hubris."

There are no scientifically rigorous outcome studies to determine either the actual efficacy or harm of "reparative" treatments, according to the American Psychiatric Association. However, there are numerous reports of individuals who have claimed to change, those who claim that attempts to change were harmful to them, and others who claimed to have changed and then later recanted those claims.

While Spitzer has noted cases where people have had bad experiences with "reorientation" approaches, he acknowledged that in other cases, individuals have "felt they were helped by having therapy available that took their religious values seriously."

The American public remains divided on the issue but is showing growing tolerance for the homosexual lifestyle. A recent CNN poll revealed that for the first time in its polling, the majority of Americans (56 percent) said they do not believe sexual orientation can be changed.

Results of the milestone research by Stanton and Yarhouse will not be released until Thursday at the American Association of Christian Counselors (AACC) World Conference and will be published this month by InterVarsity Press, the publishing company linked to InterVarsity Christian Fellowship.

Knowing the results of the study will generate controversy, Jones and Yarhouse have thoroughly described the rationale for their procedures, according to a released statement.

George A. Rekers, professor of Neuropsychiatry and Behavioral Science Emeritus at the University of South Carolina School of Medicine, states that the study "meets the high research standards set by the American Psychological Association that individuals be validly assessed, followed and reported over time with a prospective, longitudinal outcome research design."

Endorsing the upcoming book, Dr. Warren Throckmorton, a noted expert in sexuality counseling, stated, "While the authors fully acknowledge that change in sexual attractions did not occur for some individuals, they offer cogent and compelling reasons to believe that participation in religious ministry resulted in durable changes for others. The Jones and Yarhouse study will set the standard for all future work in this field and demands a serious reading from social scientists."

Publisher Bob Fryling commented, "In a highly politicized environment, this book is another 'inconvenient truth' of scientific research data countering prejudice and ignorance."

"Ex-Gays?: A Longitudinal Study of Religiously Mediated Change in Sexual Orientation" will be available to the public in October.