This is far from a hypothetical exercise.
Consider, for example, this current story from the Los Angeles Times...
Bedrock of a Faith Is Jolted
DNA tests contradict Mormon scripture. The church says the studies are being twisted to attack its beliefs.By William Lobdell
Los Angleles Times Staff Writer
February 16, 2006From the time he was a child in Peru, the Mormon Church instilled in Jose A. Loayza the conviction that he and millions of other Native Americans were descended from a lost tribe of Israel that reached the New World more than 2,000 years ago.
"We were taught all the blessings of that Hebrew lineage belonged to us and that we were special people," said Loayza, now a Salt Lake City attorney. "It not only made me feel special, but it gave me a sense of transcendental identity, an identity with God."
A few years ago, Loayza said, his faith was shaken and his identity stripped away by DNA evidence showing that the ancestors of American natives came from Asia, not the Middle East.
"I've gone through stages," he said. "Absolutely denial. Utter amazement and surprise. Anger and bitterness."
For Mormons, the lack of discernible Hebrew blood in Native Americans is no minor collision between faith and science. It burrows into the historical foundations of the Book of Mormon, a 175-year-old transcription that the church regards as literal and without error.
More at the link.