When Schoenberg talked about the "emancipation of the dissonance" - to try to explain this in layman's terms - he was saying that there is no objective difference between a dissonant sound and a consonant sound: in other words, that it was all conditioned. The tension and release of moving from discordant sounds to consonant sounds is at the core of the western music tradition. It's part and parcel of virtually every hymn or psalm in every Christian songbook of the last 500 years, and it's part and parcel of virtually every classical work from Palestrina to John Williams, part and parcel of jazz, rock n roll, virtually every noteworthy sound track, even much hard rock and heavy metal. To deliberately break with this is a radically deconstructionist move. I don't believe the western music tradition is inherently superior just by virtue of being the western music tradition. But all civilizations, regardless of scales or tuning systems, know that some sounds are consonant and others aren't. The precise notion of what is euphonious or cacophonous may vary from civilization to civilization, but the idea is a universal one. Schoenberg dispensed with it. That goes against nature and against created order.
I wouldn't say that's what Schoenberg meant by the 'emancipation of dissonance'. There is of course a difference between dissonance and consonance, but he merely meant to point out that it is a difference of degree and not kind, which from a technical standpoint is true. I don't know of any musicologist who would hold to the assessment that Schoenberg was a radical revolutionary who marked a decisive break with the entire western music tradition, anymore than someone like Beethoven or Wagner. People have said that about Schoenberg, but it's largely believed to be a caricature, and I think listening to his music alongside the music of his day would prove that to be the case. 'The tension and release of moving from discordant sounds to consonant sounds' is quite broad and I don't think it sums up the core principles of the Western tradition. Firstly, it doesn't make sense in an early music context, with something like Gregorian Chant, which is 1) purely homophonic and 2) modal rather than relying on the major chord. Lots of modern music draws upon this earlier modal tradition, as well as music from other cultures to which our tonal framework doesn't apply. Secondly, as Schoenberg has pointed out, and which is accepted by the vast majority of musicologists, the sounds which are consonant and dissonant rely entirely on the surrounding context of the music itself (especially in its relation to the tonic, which is what we really mean by 'tonality' in the Western tradition).
Schoenberg certainly wrote in a new style, which discarded much of what previous musicians were doing, just as Beethoven did, but it didn't throw out some necessary aspect of the tradition which everyone else kept to. It certainly was not his intention, and I don't know of any musician who would make a serious case for that. He was reacting to the fact that the music of his day was using 'tonality' without even understanding how it was supposed to be used, which led to some pretty awful late romantic music. Tonality really had completely lost its way after Wagner, and I don't envy Schoenberg's position (or Stravinsky's for that matter), because music had genuinely gotten itself stuck in a cliched rut. If you listen to Schoenberg's total output (he himself started as a romantic composer), you will hear how subtle the transformation actually was between late romantic tonality and his new 'atonal' style. In any case, it certainly was not a 'deliberate' break with tradition, as you claim. He saw himself as continuing on the work of Bach, Beethoven etc., but just in the logical next step, and most of his interpreters from what I can see would agree on this point. A good place to start would be his book on harmony (which is remains probably the greatest book on Western harmony ever written, and still used in universities today - it is anything but radical). Or you could read his essays where he talks about this stuff (I think it's in
Opinion or Insight? where he talks about emancipation of the dissonance, and from memory I'm pretty sure he should lay out the idea there that dissonance and consonance are not opposites but must belong together, which is not a very radical concept). I would also recommend watching Glenn Gould's stuff on Youtube about him, as well as Leonard Bernstein's lectures on 'The Unanswered Question', which talks about Schoenberg in detail towards the end, and explains how music arrived there quite logically.
I don't want to fall back into the error of engaging in overly technical conversation on a forum that is about theology and not music. I do think there is a fundamental difference between the Second Viennese School (Schoenberg/Berg/Webern) and the late Romantics / early Moderns (Debussy/Wagner/late Scriabin). There is a large gulf between music that stretches the bounds of tonality and music that deliberately dispenses with it altogether. I'm not saying the philosophical underpinnings of Wagner are necessarily any better - just that there's still a measure of restraint in the late Romantics that prevents some aspects of their musical philosophy from being carried out to its logical conclusion. (Ditto for Beethoven.)
I agree with you about technical conversation, and I apologise for my long responses. But in a way, that is the point that I'm trying to make. This conversation should make it clear that any discussion about beauty in music has to rely on actual musical arguments, not just broad generalisations. So it has to be technical in order to be actually accurate. As a musician (though a very amateur one), I find that what is sometimes claimed by Christians about art in sweeping statements is just not true, musically speaking. If you want to argue against Schoenberg's music, then that's fine, but you'll have to give references to actual scores, and his works, and scholarship about him - and most importantly, try to understand as best as possible before you critique, like you would with a book, which would involve listening attentively and charitably to lots of his music. My point in all this is to highlight just how far removed all this is from theological concerns. I don't see how you could label Schoenberg's music as 'un-Christian'. What has one's opinion on western tonality got to do with Christian faith and practice? I don't know where you would even start to make such an argument, seeing as it is concerned so much with music theory, and the music in question has no lyrics. You rightly point out that western music was heading in Schoenberg's direction since Beethoven, but argue that earlier composers like Wagner still had a measure of tonal restraint which Schoenberg didn't have. Am I right in understanding you to say that this is the point in music which can be considered no longer 'Christian', because it has embraced some sort of relativism? To say that something isn't in accord with Christian values is quite a strong claim, and implies that it's something to be avoided and detested, something sinful. You can make a case that it is ugly if you want, but such a case relies on complex musical arguments, as well as the judgment of human reasoning, which is fallen and unreliable. Apologies if I'm misunderstanding, it seems that from a Christian standpoint you are saying:
1) The Bible makes the claim that beauty is Christian (e.g. Phil.4:8-9);
2) Schoenberg's music is not beautiful;
3) Schoenberg's music is un-Christian.
I understand that this is laying it out very simply, but notice that all the argument is surrounding the second premise, not the first. That's what I'm disputing, and it's a completely musical subject which the Bible says nothing about. I know that Turretin allowed for the whole argument to be Biblical/theological if the minor premise was philosophical, but if this was the sort of thing he was talking about, then I don't see how he could justify it within the limits of
Sola Scriptura, seeing as the entire argument is now hinging on the truth of a completely non-biblical and purely philosophical premise.