Another take is something like "divine cold war": The deities feel rivalry, compassion, hate or friendship among each other, just as villains and heroes on the material plane.
But unlike mortals, they're beings of vast energy, tied to reality itself, therefore outright battle among gods will cause tremendous havoc, which will affect to lifespan of the deity in a less enjoyable way or diminish their powers, and unravels their creations, their portfolios and so on.
Good deities don't want that because of compassion for their ilk, for reality, and the mortals, evil gods don't want it because of pride, fear of death (they have no afterlife, after all), and greed for power.
Therefore, the deities do not battle each other face-to-face, but they still feel the need to crush their opponents, at least, they want to annoy them - and they do so by proxy: They imbue mortals (clerics, paladins and blackguards) with a tiny sliver of their might to wage war for them. And the mortals gladly accept for a variety of reasons.
Of course, YMMV, since the answer is highly campaign-specific. But if you're dealing with non-faith-empowered (FR-style) gods, and rather place them at "greek soap deities" than "inscrutable higher entities", the "divine cold war" is a somewhat reasonable model.