What, exactly, happens when a being composed of pure magic comes into contact with an AMF? With normal wizards and such, with AMFs that cover a 4' radius and last Xd6 rounds, yeah, they just snap it like a twig and smack the wizard. How about a permanent AMF with a duration of 220k - 250k+ miles (OP said he wanted it to extend about to the moon)?
I'd like to think that the reason humans haven't been exterminated at all is because, the first time a literal god did try to wipe out Earth to protect their chosen species, they didn't expect such a powerful AMF, teleported directly to out planet, and then got torn apart by the sheer force of our AMF. It sets up a few neat ideas:
1) Race Z hates us, utterly, and absolutely, hates us, for having killed their god (accidentally though it may have been). Even so, if they want to stay competitive in the magical arms race, they have to rely on humans. This kind of tension can create some great story hooks.
2) Collectively humanity killed a god. On accident.
The next idea requires a concept: patron-gods, elemental-gods, and conceptual-gods. Patron gods (Orcus, Llolth, etc) are tied to a specific race or species. Elemental gods are tied to an element, or material like fire, wood, light, or stone. Conceptual gods are tied to ideas; things like compassion, love, or war.
3) As it just so happens, once we begin to integrate ourselves into the magic-active universe, we discover the existence of The Forgotten One, the patron-god whose chosen have long since passed into antiquity... and he happens to be named Yahweh.