I read the question as "is the argument for (scientific) materialism circular and question begging." I believe the answer is yes.
Materialism explicitly states (virmaior comment: WHERE?) that the universe is an isolated physical system beyond which nothing exists; that is, there is nothing above and beyond physics (i.e. space, time, matter, energy, and the lawful regularities applying to these). This is a metaphysical commitment that nothing exists except for physical objects and their interactions within a closed universe.
It follows that human beings are merely clumps of matter. Moreover, it would mean that any supposed unobservable spiritual world is mere fiction occurring within the brain.
Another capacity in the brain is our ability to use reason. Reason, here, means a handful of laws in logic (e.g. material implication, conjunction, negation) (virmaior comment: this is a dubious understanding of "reason" as applied to what people do). But if the above is true, we cannot warrant the trustworthiness of these laws of logic because this happens in the brain (which is merely a part of this material physical system).
Wittgenstein argued that normative or evaluative statements are not true statements, rather they are, in his words, "pseudo-statements" expressing, if anything at all, sentiment or emotion (virmaior comment: citation to Wittgenstein? This sounds more like Russell or Carnap). His argument reflects the naturalistic fallacy. My addition to this concept, though hardly original, is that truth values themselves (i.e. "true" and "false") are themselves evaluative even if applied to what Wittgenstein described as real propositions (virmaior comment: how does this entire paragraph contribute to your answer?).
In a closed universe in which only physical entities and their interactions exist, evaluations of truth or falsity are merely contrived by our brains. Matter has no capacity to determine truth or falsity, nor laws of logic, or anything at all. As such they have no merit (virmaior comment: this seems to be question-begging.).
Let us consider the idea that God exists as a being whose essence is nothing at all like the universe and whose existence precedes His creation of the universe, and the universe conforms to His specifications so that He is free to enter and exist it at His pleasure, then truth (and falsity) and logic and all of our reasoning is plausibly warranted, but only if He has chosen to reveal this to us. Nothing merely material can provide a universal and immutable standard of truth and logic - only an immaterial God responsible for creating our brains can provide this standard. Moreover, God must enter into the universe and reveal to humans that this is the case, and leave an enduring record of this standard against which we can logically test all propositions (i.e. declarative statements of fact, both descriptive and prescriptive) for veridicality or falsity (virmaior comment: **it seems like this could just be reduced to: if there were a god, then we would have the possibility of objective evaluative judgments. ).
The materialist argument for scientific materialism begs the question on account of his belief that logical reasoning shows it to be true (virmaior comment: this is redundant. you've already made the claim two paragraphs above). He (virmaior comment: who is he?) effectively has assumed the truth of materialism as a key premise in his attempt to prove his conclusion that materialism is true. He assumes that human brains are clumps of evolved matter, and it's cognition is not patterned after a creator God's own, though obviously superior, cognition. Therefore, logically speaking (and I obviously believe in the existence of the God just described) (virmaior comment: **the point of this SE is not to share our views per se, so the question is what is the argument for what you're saying ... **), the argument supporting materialism first assumes the existence of a thinking brain brought about through materialistic processes, then proceeds to use this brain to argue for scientific materialism.
(+ virmaior This forum (virmaior comment: this is not a "forum" per SE. It's an SE). comment is a little bizarre. My writing meets the standard of prescriptive grammar most universities expect: ... (virmaior comment: it's grammatical, but that's not identical to saying university professors would like it. I would, if you were taking my class, tell you to edit it and make the same comments I've made here (and probably more because that would be a part of my job) whereas here I'm just volunteering). If my prose is difficult to follow, I suggest that this has less to do with my writing and more to do with certain readers' unfamiliarity with slightly more sophisticated morphosyntactic constructions which I have intentionally designed for sake of economy (virmaior comment: it's hard to believe your goal with this writing style is economy).)