What Is the Immaculate Conception?

The reason that she's fighting so hard isn't just for Joel. It's because the fireflies, all of these people, Tess, Marlene, believe in her. And we know that humans who think they are a Messiah nine times out of 10, 99.9% of the time, it goes bad. What happens if Ellie does meet the fireflies and they do treat her as this deity? "That almost to me was kind of what awakened a certain amount of Ellie's humanity"