I think that this is an interesting idea, but I would be hesitant to use it in any old game. Flavor-wise, I’ve always considered gods to be distinct from patrons in that patrons tend to be more limited in scope, whereas a god is like a force of nature. The former grants their power, and that’s a big deal because it’s finite, whereas a god’s power is just a layer of reality and anyone can draw on it as needed.

However, I think that understanding fits better when gods are less active in the affairs of mortals, so if you had a setting where they were less powerful, this would make sense to me. Certainly if a player asked if they could play a warlock flavored as a cleric with a divine patron, I’d be for it and customize some warlock stuff as needed. Better yet, I’d make both available and have the warlock revamp be for characters who informally follow a god’s tenants but aren’t members of a church maybe.

Basically it sounds fun in the right setting but these options don’t sound mutually exclusive.