I would simply challenge the very idea of an irrelevant issue. Whilst it might be possible to divide knowledge into discrete packages bounded by logical distinctions in a purely objective, idealised realm, human beings just get the one brain in which every single experience, experiment, and calculation impinges on every other. From a lofty ivory tower you may think that my opinion on the voice casting for a Pixar movie has nothing to do with my analysis of the ontological argument but you cannot possibly be certain that it is the case because that's just not the way thinking works. In fact the greatest intellectual leaps are often made by bringing into contact apparently totally unrelated spheres of experience. To quote but one example, Richard Feynman would not have been half the scientist he was had his fields of study been schismatically organised for him.

I would counter with the observation that there exists no human society that does not use spoken language which suggests that variations are in fact finite and quite possibly do not exist at all. The human brain is pre-programmed for spoken language and grammar to such an extent that where no common language exists children are capable of creating one without supervision or guidance at all. Writing, semaphore, morse code and other signalling systems are in no way replacements for spoken language but simply ways to transmit words across distances which they do remarkably inefficiently (just remember how difficult it is to include tone in emails!)

xtreme violence, barbarity, murdering, raping, pillaging, etc. are evil.

Not according to Plato, the Neo-Platonist school (on which our forms of government and systems of justice are, after all, largely based), Augustine and a host of other theologians and philosophers they are not.

Apart from it being completely impractical, unworkable, and utterly corruptible, you mean?

On the contrary, I find the Greek concept just as open to the same criticisms. Being content with the way things are 'meant to be' and being the person we are 'meant to be' is every bit as much a life of denial as happy, clappy ignorance of all that assails us.

It seems a tad convenient that God apparently doesn't mind in the slightest ceding the decision on what is evil (if indeed such a thing even exists) and who should live and die as a consequence to a bunch of hubristic judges and then picking up the pieces after they're done.

The reason I endorse this view is that humans in general (excluding people with unusual mental disorders,etc),act in ways which could be logically dissected to demonstrate that the real purpose which lies behind them is the attainment of some form of happiness.

You exclude the very real possibility that happiness and dedication to its attainment is itself a mental illness, then? You certainly seem to be claiming that what 'humans in general' do is by definition the most rational and true expression of their purpose.

As C. S. Lewis once observed, it could be a great mistake to assume that God (and here you may substitute whatever principle you wish from Mother Nature to the selfish gene and back again) intends us to be happy. Happiness is, after all, nothing but a delusional state which denies reality and in its worst expressions (where it reaches near cultic status) actively seeks to hide reality from us all. It is no more than a permanent state of denial which seems to be a pretty poor thing to be considered the purpose or meaning of life! And that's before you even start to consider the narcissism, egoism and selfishness it tends to engender!

I would still support that the serial killer is publicly executed, so that other criminals are shown that justice is not to be messed with

The problem here is that the effect you seek is demonstrably weak at best and non-existent in most cases. There is no historical evidence at all that public execution, which let's not forget was at one time an event on a par with a modern pop concert, in particular, or executions in general have any deterrent effect. In fact, the very opposite was often the case. As the saying 'might as well be hanged for a sheep as a lamb' attests, criminals were prone to upping the ante committing more serious crimes on the basis that they were risking everything anyway so they might as well make it worth their while.

In any case, I have never understood the logic of death as the ultimate punishment, especially in an increasingly atheistic society where there is no question of hurrying someone on to face divine judgement (always a dubious theological justification in an event). Far from facing the perpetrator with their own guilt and remorse death simply releases them from any responsibility for reparation. It is those who are left behind who are being punished in reality and on the flimsiest of excuses, guilt by association. That is not justice, at least not by any sane, rational definition.

I think you need to be clear that placebo's do not cure mental illnesses which have physiological bases. But then nor do most (if not all) drugs used in such cases. The best outcome in cases of schizophrenia or bipolar disorder, for example, is to establish control over the frequency and severity of attacks and placebos are rarely, if ever, as effective in such conditions as direct correction of brain chemistry. Placebos are always most effective in patients who essentially think they are ill, the worried well who consume by far the greatest part of medical practitioners' time and energy, because they make then think they're getting better, although as that in itself is largely simply the effect of being taken seriously, given professional time, and just having someone care, if only for a brief time, it's questionable whether any physical 'pill' need be administered at all. After all 'talking therapies' are often equally effective.

The infinite universe may be theorised endlessly but it simply falls apart in science. If the Universe is infinite then there is no entropy. Barring a complete overturning of every basic concept of astrophysics there is entropy in our Universe and so it must be finite. Incomprehensibly vast but finite.

I believe existence contains all logical possibilities. This seems to me to be the default ontological state.

How can such an existence contain the logical possibility that there is no existence or that the instantiation of one logical possibility excludes the instantiation of all other logical possibilities? The semantic sophistry of 'subsist in a non-physical state' does not get you off the hook here. The word "contain" is meaningless if it does not require instantiation, at least in the context of "existence". All you are saying is that all logical possibilities exist as logical possibilities a trivial truth of no ontological significance whatever.