My grandma has that same religion. In the late 1980 she was visiting Berlin, and coming back she had said: "On the western side the wall was full of graffitis and really ugly, but the eastern side of the wall was completely clean. That shows where people are happy and where not."
They would definitely manage to protect their mind from any information contradicting their religion. Once the brain's gone, the brain's gone. There's a small chance that a new one will grow to fill the hollow, but that's not something that can be influenced from outside the brain.