I had a handful of questions, mainly regarding Neo-Platonism, and partially it's impact on Christianity.
Thank you for these - these are interesting questions!
1. Plotinus' image of Plato seems to be largely a characterization used to help make his (Plotinus's) point, far removed from the real man. To what extent would you say the philosopy of Plotinus is Platonist in name only?
It really depends on what you mean by "Platonist". Philosophy in late antiquity always worked like this: philosophers were divided into the various "schools" and spent their time studying the writings of the great founders of the past. Philosophy consisted entirely of exegesis, at least in theory. In practice, of course, they were all reading their own ideas into the texts (at least to some extent). Now if "Platonist" means "a member of Plato's school", which is what it meant in antiquity, then Plotinus was certainly a Platonist because he chose to do his philosophy on the basis of Plato's works rather than those of Zeno or Aristotle or whoever.
Of course Plotinus' philosophy was not really the same as Plato's - but equally, it was not entirely different. The question then is how similar to Plato someone has to be to count as a Platonist. If you have to believe, for example, that all universals are eternal Forms, then neither Plotinus nor any other Neoplatonist was a Platonist, since they denied that there were Forms of base, mundane, or artificial things. If, on the other hand, believing that form is logically prior to matter is enough to be a Platonist, then they were. Plotinus believed in an ideal, eternal realm that logically precedes the material, sensible realm and which explains it, and I think that that may be usually regarded as the defining characteristic of Platonism. But this is a matter of labels.
2. How would a man like Dean Inge reconcile his Neo--Platonist beliefs with modern discoveries in astronomy? Would they solely reject portions of the canon referring to celestial bodies as "gods"?
I don't know much about Inge so I can't help you with him in particular. But there is no Neoplatonic "canon" in anything analogous to a religious sense. A Neoplatonist is not obliged to believe everything that the ancient Neoplatonists believed. Neoplatonism has certain distinctive features - a belief in the ideal and eternal realm as mentioned above, together with the notion that the material realm is related to it by emanation and return, and that existence, beauty, and goodness are basically the same thing. You certainly don't have to believe in the Ptolemaic system or pagan theology to be a Neoplatonist, even though the original Neoplatonists did. Obviously there have been many Christian Neoplatonists, such as Gregory of Nyssa, Augustine of Hippo, Pseudo-Dionysius the Areopagite, Eriugena, Marsilio Ficino, Pico della Mirandola, and so on and so forth. They didn't think that Neoplatonism required the pagan elements of its founders, or indeed of Plato himself, or that it could not be combined with Christianity.
3. I know Plotinus spent some time arguing against the Gnostics, but could you perhaps elaborate a wee bit on their relationship?
Enneads II.9 is a treatise against the gnostics - in fact probably against Valentinians, to be precise. Plotinus' objection to them is that they think that the physical world is evil and that it was created by an evil or at least non-benevolent creator. So in that treatise he produces a battery of arguments for the goodness of matter. These arguments are, arguably, not entirely consistent with what Plotinus says elsewhere about matter. In fact Plotinus' pronouncements about matter are the subject of considerable interpretative debate, since they are complex and frequent - perhaps a bit surprising, since at least one of Plotinus' official views on matter is that it doesn't exist. For something that doesn't exist, it interests him a lot. At any rate, Plotinus does characterise matter as shadowy, insubstantial, and decidedly not good; it is, among other things, the principle of non-being and of the lack of goodness. However, he does not have the stomach to go so far as to make it actively evil, which is why he attacks the gnostics for doing so.
4. Bertrand Russell summarized of Plotinus' teachings that "Matter is created by Soul, and has no independent reality." This seems to be kind of sort of reminiscent of some of the interpretations of the Schrodinger's Cat experiment. Regarding time, St. Augustine seems to be similarly prescient. Is there any present thought devoted to linking these men and their ideas with modern day physics? I understand this may be outsider your realm of expertise.
The Schroedinger's Cat thing isn't meant to show the unreality of the physical world - it's meant to show up the absurdity of the idea of superposition, by pointing out that if you allow superposition at the sub-atomic level then there are circumstances in which there would also be superposition at the super-atomic scale. It's all very well to say that a sub-atomic particle may exist in two contradictory states at the same time, but it's another matter entirely to say that a cat may - but if you accept the former you must accept at least the possibility of the latter. So, at least as I understand him, Schroedinger was a realist about the physical world - he didn't think that the state of a cat could seriously depend upon our perception of it, and therefore the state of a sub-atomic particle couldn't either.
Anyway, you are right that there are at least superficial similarities between the Neoplatonic belief in the relative non-reality of the physical world, and its dependence upon the mental, and some interpretations of modern quantum physics. And in fact there is great interest in some quarters in these similarities. Philosophy of physics is a burgeoning field at the moment and some philosophers of physics, and indeed physicists themselves, are interested in relating the philosophical implications of modern physics to older philosophical traditions. For example, there is a group of physicists at the University of Vienna who are interested in these issues and who have recently set up a new Vienna Centre for Quantum Science and Technology to investigate them. This and other, similar centres are mainly interested in the new philosophical implications of cutting-edge physics, rather than in antiquarian issues, but some figures involved in this work who are more from the philosophical side than the physics side are also interested in relating it to traditional philosophical ideas.
5. According to Catholic dogma, the Church never changes its teachings, is that correct? If so, how do they reconcile their modern rejection of some of the teachings of Origen (and by extension Jerome) as well as those of Augustine?
From a Catholic viewpoint, Origen certainly did not speak for the church - he was simply an individual writer with ideas of his own. The same is true of Jerome and Augustine, though to a lesser extent since they are considered Doctors of the Church and therefore pretty reliable characters. Nevertheless, they are not infallible. No individual is infallible apart from the Pope on the rare occasions when he infallibly defines a dogma. Infallibility resides in the church as a whole, and is best expressed in the decrees of ecumenical councils. So from the Catholic point of view there's no problem with the idea that there are errors in the works of the authors you mention - but there would certainly be a problem if any errors were found in, say, the creeds of the ecumenical councils.
Well, unless you think God has error (This typed before I read your full argument, which I will do after completion of this post.)
I don't want to get into two different discussions about the same topic with the same person, so I'll refer you back to the discussion on this topic in your Evangelical thread, where I've addressed this argument.
I don't think Sola Scriptura teaches that you shouldn't believe anything else. For instance, if you tell me the sky is blue, well, that's not in the Bible, but I still believe it
The point of Sola Scriptura is that nothing else, whether reason, logic, or tradition, is INFALLIBLE. There is a difference between a specific teaching being true and the teacher being infallible.
No, Jehoshua is right on this one - sola scriptura means that the Bible (and only the Bible) contains all the truths relevant to salvation. Thus:
The Westminster Confession VII. said:All things in Scripture are not alike plain in themselves, nor alike clear unto all; yet those things which are necessary to be known, believed, and observed, for salvation, are so clearly propounded and opened in some place of Scripture or other, that not only the learned, but the unlearned, in a due use of the ordinary means, may attain unto a sufficient understanding of them.
It's got nothing to do with infallibility. One could, at least in theory, believe in the principle of sola scriptura and yet also believe that the Bible contains errors. (I don't know if anyone has believed this, but I see no problem with it.) And one can certainly believe that the Bible is infallible and reject the principle of sola scriptura, since that is what the Catholic Church does.
So sola scriptura does not say that there are no truths found outside the Bible - you're right about that. However, it does say that there are no truths relevant to salvation found outside the Bible. In practice that means everything to do with Christianity. So when I said that the principle says one should believe only what is in the Bible, what I meant was that it says that there is nothing outside the Bible, relevant to salvation, that one has to believe. (I didn't express it very well.) That is why it is a serious problem for this doctrine that the Bible itself does not contain it, for the reasons already given. The only plausible way around this that I can see is to say that the principle of sola scriptura is not itself relevant to salvation. How plausible that is, however, might be a matter of debate.
How can you know that?
No-one can know for sure that Paul did not write 2 Timothy, of course. But we can examine the evidence and draw conclusions about what is probable on the basis of that evidence. The evidence strongly suggests that Paul did not write 2 Timothy (or 1 Timothy and Titus, the other Pastoral Epistles).
With all such cases, there are three major reasons why scholars question the text's authenticity:
(1) Language and style. If the text uses vocabulary noticeably different from that used by the author in other writings, or if the style is noticeably different, that may suggest that it is by a different author.
(2) Ideas. If the ideas - philosophical, theological, or otherwise - in the text differ noticeably from those expressed in other writings by the author, that suggests that it is by a different author.
(3) Historical circumstances. If the text seems to imply that it was written under historical circumstances in which the supposed author did not really live, then that suggests that it is by someone else.
None of these things is "proof" individually. After all, a single author may use different vocabulary and different writing styles in different situations. An author may change his mind about important things over time, or say different things to different people. And our knowledge of historical circumstances is incomplete, so we cannot always say for certain that an individual could not have referred to things that we think he could not have. But when you get all three of these factors at the same time, and when they are all particularly striking - as is the case with the Pastoral Epistles - then the case against their authenticity becomes overwhelming. There is just no good reason to think that they really are by Paul and many good reasons to think they are not.
If you are interested in the details, this page outlines them. This is a good website for giving summaries of scholarly opinion regarding New Testament writings and related texts in general. The links given there are also worth following if you care about these matters.