Joe Leigh Simpson, chairman of obstetrics and gynecology at Baylor College of Medicine in Houston, is a church-going Presbyterian.

But thanks to a few conferences he attended back in the 1980s, he is known in parts of the Muslim world as a champion of the doctrine that the Quran, Islam's holy book, is historically and scientifically correct in every detail. Dr. Simpson now says he made some comments that sound "silly and embarrassing" taken out of context, but no matter: Mideast television shows, Muslim books and...