A thorough new study, entitled Ex-Gays? by Dr. Stanton Jones and Dr. Mark Yarhouse has been published. It examined participants in Exodus Ministries' ex-gay programs and investigated any psychological effects resulting from them.
I'll summarize briefly: The authors attempt to basically answer this question: "Is it impossible for a homosexual to change to a heterosexual or become celibate without psychological harm?" The book concludes that Exodus International's ministry has, on average, succeeded in doing just that. This is a scientifically valid and thorough study that will cause problems for those who hold that reparative therapy is always bad medicine.
I'll let the authors speak for themselves. There's plenty of video and other related content here. This particular video speaks to their findings most extensively.
I also link to a pretty thorough debate here and here between the authors and Dr. Patrick Chapman, author of Thou Shalt Not Love: What Evangelicals Really Say to Gays. Those links are the most helpful if you want to get into the issue in great detail. You can see part 2 of the debate here and here and part 3 here and here.
Hopefully we can have some reasonable discussion about this issue, particularly with the inspiration provided by the example of excellent work and respectful debate demonstrated by the authors. I understand that Exodus International and other ex-gay ministries are a hot point for some of our readers. Personally, I haven't gotten through the entirety of the material linked to myself.
