We have a long-running D&D 5e game in which there is a Paladin who worships a god invented by the Kuo-toa.
Per the Monster Manual:
Kuo-toa worship gods of their own insane creation, but if enough kuo-toa believe that a god is real, the energy of their collective subconscious can cause that god to manifest as a physical entity.
In our campaign, the Paladin, who is not a Kuo-toa but worships a god created by them, increasingly believes that the god does not represent what he thought it did. It turns out that the god is evil. This is creating a crisis of faith for him, and he will likely turn his back on the god entirely.
This is different than the Oathbreaker as described in the DMG, which is about Paladins who turn towards evil. The character has not broken his oath and is still following the tenets, but does not believe in the god.
My question is: If a Paladin abandons belief in a god, but does not seek to "pursue some dark ambition or serve an evil power," as stated in the DMG's Oathbreaker section, what happens?
Without faith, is he still a Paladin? Does he lose his magical abilities? Or should the character be re-classed into some other martial class upon abandoning his faith?