There have been lots of evidence over the years that physical injury to the brain causes people’s behavior to change, often for the worse. The classic example of this is Phineas Gage, a railroad worker who had a spike driven through his frontal lobes. Before the accident, he was polite and industrious; after he was crude, irresponsible, and frequently started fights. A cursory web search can find details of this case.
More recently, researchers have found degenerative brain maladies can trigger dramatic changes in personality, including changes in religious belief:
http://www.cnn.com/2001/HEALTH/05/08/science.self.reut/index.html
How do Christians, or members of any religion who believe theirs is the only way to salvation, reconcile the fact that someone may change their behavior, even their religious beliefs, as a result of a physical brain malady or injury they have no control over?
Joe Shmoe is a good Christian, but then through no fault of his own is afflicted with frontotemporal dementia, and becomes a Wiccan. Do Christians believe Joe is damned, even though his change of belief was clearly not via free will?