So here's what happened. One day, I was struck by a bolt of handwavium, and it caused me to become immortal (unkillable by any means). Shortly after that, a majority of civilization was wiped out by global nuclear war, and I got buried under tons of rubble for a long, long time.
I emerged from the rubble eventually, and encountered a small tribe of survivors who had somehow managed to rebuild a very simple civilization. Their initial reaction upon seeing me, alive despite my lack of protective clothing in a harsh, post-nuclear apocalypse landscape, was one of awe. They welcomed me into their homes readily enough. Their language has evolved slightly, but sufficiently rooted in English that I was able to communicate with them after a bit of trial and error.
I learned that they have no religious belief - the teachings of Christianity, Buddhism, or whatever have you did not survive the apocalypse. They are pragmatic people who seek simply to eke out an existence on a dying planet.
I am of slightly above average intelligence, unfortunately with no special skills or talents except for being immortal. I remember things from before the apocalypse, which no one else in the tribe does. With this, how do I establish myself as a living god among these survivors?