I think there is pretty solid evidence that he’s just copying other peoples’ shit.
1. The story sounds very much like a Solzhenitsyn story (via Sullivan)
Leaving his shovel on the ground, he slowly walked to a crude bench and sat down. He knew that at any moment a guard would order him to stand up, and when he failed to respond, the guard would beat him to death, probably with his own shovel. He had seen it happen to other prisoners.
As he waited, head down, he felt a presence. Slowly he looked up and saw a skinny old prisoner squat down beside him. The man said nothing. Instead, he used a stick to trace in the dirt the sign of the Cross. The man then got back up and returned to his work.
As Solzhenitsyn stared at the Cross drawn in the dirt his entire perspective changed.
The other possibility is that McCain really thinks this happened to him, and can’t differentiate between something he read and something he actually experienced. I’m pretty convinced that he experienced no such thing. As Rickrocket notes: “Somehow I doubt that Alexander Solzhenitsyn heard John McCain’s story and copied it.”
My guess? No one will ask McCain about it for fear of being accused of questioning his patriotism.