Whether something is "worthy of devotion and reverence" is a personal opinion not an objective quality.
But that is at the heart of what someone means when they say things like, "Well, of course you're a powerful magical being, but are you a
god?" A god
deserves worship, and hunting after proof-of-divinity is precisely that, the search for the
objective quality of divinity, not merely "personal opinion."
An entity being inherently worthy of devotion and reverence
is what they're looking for. It's certainly a trope, and practically a subgenre of sci-fi (and to a lesser extent fantasy) that "powerful being who demands and/or receives worship" is not at all sufficient qualification for being "a god."
"What does God need with a starship?" You don't ask this kind of question if you don't have an idea that there is an essential
something, an objective quality that actually merits devotion and worship (at least from some group of folks, not necessarily from absolutely everyone.)
Depends on the definition. If warlock magic was similarly channelled like cleric magic then indeed one could reasonably think these beings that are source of that power as minor deities. It is just semantics really.
But that's the point. If power alone becomes "just semantics really" then power does not a god make. Obviously, one would expect a god to have some degree of power; but that makes it a necessary, not sufficient, condition. The sufficient condition, as stated, is being
inherently worthy of devotion and reverence. Y'know, characteristics like "truly, actually the uncreated creator-of-all-things" or the like.
In something like the World Axis, deities are in effect living concepts. Pelor is not simply a powerful being who can do sun-related stuff. In a very meaningful sense, the
essence and
nature of hope, of the sun, and of life, are part of him--and he is part of them. Some part of what those things
are is embodied in him--and if he were to be truly destroyed, the part of him that is in them would die as well. Those things themselves would not necessarily die, but they would most certainly be damaged. Likewise, Tiamat
is some living portion of tyranny and greed and vengeance. If she were to be truly, utterly slain, all the things she is would be lessened in the world. They would not be gone--but they would recede, because a powerful portion of what those things are had been snuffed out. Rulers would show mercy and justice to their people--or fall and be replaced by better ones. Misers would give an Ebenezer turn. Fewer bloody feuds would continue, as folk reconsider and set aside old grudges.
In my Jewel of the Desert setting, as noted, the only deity-like being that has kinda-sorta-halfway appeared in-setting (and that only privately to one specific PC) makes no claims of being able to prove Their divinity--it is a matter of faith whether you believe it is true or not. That doesn't make the fact subjective; the claim still has a truth-value. It's just not one that you can spin up some experiment and "prove" one way or the other. It must be a matter of faith.
But perhaps I have spilled too much digital ink over something that isn't actually the thread's topic. I still find it hilarious that there is this idea that a casual promise to do a thing somehow instantly results in phenomenal cosmic power. It's just...no. That's not how it works, and thoughts of gaming the system like that are precisely what would prevent it from working.