I’ll define God as an omnipotent being.
The major critique Buddhism makes against the idea of an “omnipotent being” centers on this idea: the omnipotent being is the cause of everything that happens, both good and bad; whatever you do, is foreordained and caused by this omnipotent being, whether what you do is evil or good. “Omni” means “all”, and “potent” means “power”. If a being is TRULY omnipotent, then that being has ALL the power, and we humans have NONE. We humans are simply puppets being made to do things, beyond our control.
From a Buddhist perspective, that particular notion of ‘omnipotent being’ is morally and ethically dangerous, because it takes away a person’s urge to do good and abandon selfishness.
Having said that, I would also say that, even though Christianity teaches that God is all-powerful, Christianity doesn’t teach that God actually causes everything to happen, or causes people to do good or do bad. (Unless, of course, you’re a Calvinist. Buddhists would critique the Calvinist idea of Predestination, that’s for sure.

But Catholics aren’t Calvinists.) So, from a Buddhist perspective, a Buddhist would say that the Christian idea of God doesn’t fully equate to a truly ‘omnipotent being’.
Theism is the belief in one or multiple supernatural beings great enough to deserve worship.
Let me check your definition of worship…
Worship is the acknowledgement of a being’s omnipotence and a vow of serviyude (I guess…)
Well, if a being is truly, actually, and really omnipotent, that means that it has ALL the power. If so, there can be only ONE such being, so if we go back to the “theism” definition you proposed, we can re-write that “theism” definition thusly:
Theism is the belief in ONE, All-Powerful, omnipotent being who deserves servitude.
This would get back to the Buddhist critique of an ‘omnipotent being’: if this being is
truly omnipotent, then that means that this being is causing ALL and EVERYTHING (including human actions) to happen. If that is the case, there is no human free-will, and we might as well just close-up shop and watch
Survivor.
I would suggest, however, that the Christian God, though thought to be all-powerful in theory, is not
truly all-powerful (in the way that the Buddhists define it).