Clearly there are people who just won't even be open to this idea, so no point in, or means for, any serious and open discussion with them.
As soon as communism is mentioned, the image arising in their minds is machine guns etc. which is not part of its 'definition', though might necessarily and inevitably be what it would produce? (I don't know. Can we be sure about this? Mind that all in the history one might put under its name was not communism; at most some form _claimed_ as marching towards it.)
I'm totally open to the possibility that it's totally, inherently, bad. But I just have not convinced myself yet (or by someone). But I have a suspicion that some people might feel ashamed even at the thought of not condemning it as soon as the word is heard, at any reluctance or uncertainty about its evil, not to mention at showing even a trace of interest in looking at it with a rational mind with any seriousness. If my suspicion is not ungrounded and finds some instances, this is a symptom of having suffered brainwash or trauma — more likely the former. I know, of course, you think you are immune from brainwash!
It can be that it's just the if's are too big, i.e. effectively the evils are in those if's, but we can at least agree that, if these if's are indeed true, without hidden clauses or fine print, the world would seems like a good one, can't we?
At the very least, as I asked, I don't think it's the ownership of things, per se, that we are after, but what it would secure for us, our desire for freedom with those things. On this particular and very specific argument (this and this alone), I don't think anyone with their rational mind, would disagree.
If so, let's move on carefully. We are open to the possibility that owning something is one and the only one means of securing that freedom. But I'm sure this has not been demonstrated yet. Because of this, I’m very inclined to lean on the rule that every single problem has more than one solutions, often infinitely many solutions. This means that, highly likely, even virtually certainly, securing the freedoms humans need can be achieved without owning things.
I'm not pro-communism; I'm just not entirely convinced (yet) that it's not possible. Though I'm pretty sure, even if possible, it's super difficult to achieve, and will at the very least require a very long time because it seems so fundamentally different from – as many have suggested – what human nature, on average, and as seen on a macro level or at a large scale, appears to have manifested itself (that is greed, primarily).
This sounds like that communism is bad is an axiom.
Don't get me wrong, I'm not pro-communism. But that's just as I'm not pro-capitalism.
... As Dave kindly just demonstrated 
This made me laugh. But I refrain from going further ... (with all due respect)
In reality ...
This seems to suggest that neither capitalism nor communism is (inherently) good, or bad, but some form of combination might be good. Which I tend to agree.
Humans are inherently greedy and want more.
This gets to the point, let's focus on it for a moment.
Think from scratch, is communism inherently bad?
As a means of governing humans, yes, because it is fundamentally incompatible with human nature.
This is also a good (not necessarily saying accurate) point. I agree only if based on an unspoken premise "human nature = greed".
Human nature, or
greed, lies at the core of the issue. Human seems (note I'm using "seems", not yet definitely "is") greedy. Greedy for everything material (and from there non-material), money (but wait – is money, some type of metal, or paper printed with fine patterns, of any particular value?), power (for control), fame (for vanity), sense of abundance, freedom, superiority, etc. and of course women (for men) to satisfy their lust (this is a difficult one!).
I shall put the lust (of men) for women aside for a while because this bit is difficult.
I'll also concede that all humans at least appear greedy, without exception. We want more, much more than we rationally need. But allow me to ask, is this nature or nurture? I'm not sure, are you sure? And even if it's nature, can it possibly be changed, or regulated by a rationale mind, which does not seem beyond reach?
I would argue that greed is an inevitable result of the need for survival, and when that is less a concern (though perhaps never gone away), whenever there is a scarcity of resources. This is so from the dawn of human history to date without exception. That's why it's said above, that even if possible, it will take a super long time to possibly get it. And it can't be only in a region, but must be all over the globe universally.
One question then is, given the exponential advancing of technology (particularly AI and whatever else more interruptive who knows would follow), can
scarcity of resources possibly be something of memory at some stage? If so, will
greed still stick on as human nature, even beyond the regulation of a rationale mind?