I read the same book and believed it all at the time. Now I think it was a way of trying to explain what we could not understand. A very down to earth neighbour of my mother's told us that when she was in her early twenties, a few years after the death of her mother, she awoke one night and saw her mother at the foot of her bed. Her mother said to her "Your father needs you" and she went to her father's room. She called an ambulance and he was taken to hospital
having suffered a heart attack. This woman was not even particularly religious and I never knew her to go to church or speak of any religion, but the story has always remained in my memory.
I never read the book, but the reason I said it sounded a bit grisly for a child was the fact that when I was a kid I was taken to church every Sunday with my parents and I found the whole idea of eating anyone's body and drinking their blood utterly repulsive, so I'd be interested to know how this book got round to explaining it. I do now know the significance of the Eucharist but it still makes me feel a little queasy.
As for your friend's very interesting story, it proves that you don't have to be in any way religious to have supernatural experiences. In fact I think that religion can sometimes get in the way of a person's belief in the paranormal even if they have experiences of it, and my Dad was one of them.
Talking of my Dad, two days before my mother died she informed me quite matter-of-factly that shortly before my visit she'd seen my father walk down the ward and stand at the end of her bed for several seconds before suddenly disappearing. I didn't doubt her because I knew he was letting her know that he was waiting to take her over to the other side, and I like to think that she realised that too because she did know that her illness was terminal and that her death was close, and that she found it of some comfort.