He noticed something quite curious: the gods are worn, not born, and clothes can be stripped.
Tin's 21st-edition note closes the Cookbook's deity section and is the one Carl files away for later. He observes that the gods and goddesses are Soul Armor — that the aliens inhabiting divine bodies do it the way the Intellect Hunters, the Scree and the Valtay Corporation do, wearing the gods like clothes. In theory, then, a spell designed to remove biological armor such as Take That Shit Off or Laundry Day could remove them; you would need to beat the invulnerability first, it would not hurt the god, who would revert to its programming or natural state, and nobody knows what becomes of the driver.
His practical advice: if you need a god to do your bidding, shed it of its off-world influence first, because the aliens are quite unpredictable in their manner.
Cookbook annotator, and the author of the only theory anyone has for controlling a god.