Our own brains are an excellent proof of concept that machines can be made to think. We're all machines in a way, after all - unless you believe there is a special supernatural exception for human minds.
A machine is an artifact. It is a human-built assembly of materials that have no natural inclination to work in unison. Silicon and copper, plastic and glass have no natural propensity to compute. We make artifacts, for example computers, out of these materials to serve our purposes. But they are not the materials’ natural purposes.
In the classical hylemorphic (Aristotelian) perspective, an artifact is an artificial composite of substances and thus it has an accidental, not substantial, form. Machines work as they do “accidentally”; that is, their function as machines is not inherent to the matter that comprises them. Rather their function is imposed on the disparate parts by human intelligence.
Unlike a machine, the brain is an organ, a functional part of a living organism. It (along with the body) has a substantial form; its activity is natural to it. One might say that the brain's activity is intrinsic to it, not imposed on it extrinsically, as is the activity of a machine.[1]
[1] https://mindmatters.ai/2018/10/yes-your-brain-is-a-machine-i...
So we looked and saw that life is just molecular nanotech, but what we didn't see was any tags attached to carbon chains that would say, "this molecule's natural function is to think", or "that molecule's natural function is to be a part of an organ that pumps blood", etc. Because there is no such thing like a "natural function" in the sense used by your quote, the distinction between "natural" and "artificial" is itself artificial[0], and that whole quote represents a piece of magical thinking philosophy you'd think humanity abandoned at least a century ago.
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You could just let the discourse end there - it's a strongly held belief and that's the end of the discussion. What confuses me, and maybe you can clear this up in a reply, that you still want to have a discussion about facts and reasoning. For that to happen, you would need to show that "nature" does indeed have the privileged and unreplicable position you assert it does. Just using the term "nature" is rhetorically evocative but not rationally meaningful in this context. To start with, you'd also have to definitionally delineate nature from artifice, because we humans have really been blurring those lines for a long time now and no cosmic force has stopped us yet.
Your implication that "natural" processes can never be functionally replicated or continued upon by volitional development is not supported by evidence. There is, however, a lot of evidence for the other side of this debate. We are heavily altering "nature" to suit us, and wherever we looked so far we find machinery that can be rationally understood, manipulated, replicated, remixed, and used whole or in part in our own designs. If there is a supernatural component that somehow privileges "natural" life, we have not found it yet.
and the rest of your paragraph is about artificial vs natural, which isn't even relevant, even if it could be clearly defined. Asserting "Proof by assertion is fallacious argument" is a fallacious argument.
I don't think that you understand parent comment's very valid point.
If the question is "Can genuine (human-level) consciousness be constructed out of nothing but atoms and energy?" then the only possible answers are:
1 yes, and at human scale, since a human being is a worked example of such, made from nothing but atoms and energy.
2 no, a human being is not just made of matter and energy, there is some "extra" special part to a human, call it soul, spirit, divine spark, etc without which there is not "genuine consciousness". (a)
And the whole rational project of science, going back 100s years, dismisses option 2 as sheer useless mystical mumbo-jumbo with no explanatory power at all. Therefor, option 1 is valid.
a)