Eh, for the curious he's talking about Parable. I have this somewhere but it's been ages and I forget most of the story.
This page, however, makes it clear that Galactus is doing Galactus. He came to Earth to feast but—owing to some code or cosmic enforcement mechanism—is keeping his earlier pledge not to harm the planet by his own power. The humans are worshipping him and mucking around in his name and he's banking on them destroying their own planet, mooting his earlier agreement, and leaving it available for consumption. Presumably, at some point after this, Surfer got the humans to ease up on their belief and self-destruction and Galactus left because the cafeteria closed.
It's a gorgeous comic thanks to Moebius but the writing was by Stan Lee and seems to just be religious allegory along his normal organized-religion-bad, noble-self-sacrifice-good lines.