Doubt: This is the feeling in my own stomach as I watch Stalker. Doubt that anything sacred actually exists in the Zone - which looks ordinary and real. Then belief. Doubt that the dangers Stalker warns of exist. Then belief. Doubt about Stalker's ridiculous method of finding the way. Then belief in it. Doubt that Stalkers can't enter the room, doubt that Stalker himself hasn't, can't, wouldn't. But this is the doubt of Professor and Writer. Stalker inverts the typical mystery religion when he says that only those without hope can approach or arrive at The Room. Doubt about that. Then belief.
This is so different from Prometheus in which the scientists are competent and confident and never doubt as they seek their own version of the sacred. They got straight at it and find it with ease and swiftness. This is a very different way of telling the same story.