That's fair. Let's replace 'Christianity' with 'the Catholic Church', since what you say undoubtedly applies to Protestantism, and in a less obvious way to Eastern Orthodoxy. And remember, I'm saying 'timeless if true'; the 'true' part is assumed for the purpose of this argument.
As someone who has been Catholic most of my life, it certainly applies just as much to the Catholic Church (even to there being diverse beliefs within the Church at any given time, and certainly to change over time.)
Catholicism teaches that Divine Revelation is God's Self-Revelation and therefore can't change because God can't change. Again, if it changes, then it isn't true. I'm not (here) arguing that it's true; only that in order to adhere to it, one must hold that it doesn't change. That, obviously, doesn't imply that every member of the Catholic Church believes the same thing. Nor does it imply that practice will look different in various times and places, although practice will always have the same goal (Union with the Divine Essence) and therefore be in essence the same thing.
EDIT: "will look different" should obviously be "will not look different"
> Catholicism teaches that Divine Revelation is God's Self-Revelation and therefore can't change
Revelation may not change, but the actual concrete beliefs of the Catholic Church manifestly do.
> Again, if it changes, then it isn't true.
If it changes, and it was claimed to be a universal constant, than either the before- or after-change version isn't true, sure, that's trivially true.
I said
>> The objection to your point is that the teachings of Christianity are timeless if true.
To which you said
> "The teachings of Christianity" are, in fact, not consistent across time or across subsets of Christianity at the same time
> Revelation may not change, but the actual concrete beliefs of the Catholic Church manifestly do.
The teaching of the Catholic Church just is revelation. Individual Catholics or churchmen may believe all kinds of things, some contrary to revelation and/or each other, but that's something distinct. What has manifestly changed?
> The teaching of the Catholic Church just is revelation.
No, even in the view of the official teachings of the Catholic Church, the teachings of the Catholic Church include, but extend well beyond, revelation.
If the teachings were only what was understood to be unquestionably part of the content of revelation, then there would be no teachings which were not dogmas.
Yes, that was a bad way of putting things on my part. You are correct. Better would be "the basis of the Catholic Church's teaching, and the primary part of its teaching, is revelation".
To return to the main disagreement:
>> The objection to your point is that the teachings of Christianity are timeless if true.
> "The teachings of Christianity" are, in fact, not consistent across time or across subsets of Christianity at the same time
The teaching of the Catholic Church, insofar as it is proposed as being part of Revelation, or as following logically therefrom, is timeless and unchanging. One reason is that Revelation is primarily about God (it's His Self-Revelation), who can't change.
Again, the fact that different Catholics believe different things (contrary to Revelation or each other), or that some teachings that are not proposed as being part of Revelation change over time, is irrelevant to this.
Obviously, if you claim Revelation is an "abstract ideal", then you are implicitly claiming it's false, or doesn't exist, which is an entirely different argument.
Are there any teachings that are proposed as part of Revelation, or as following logically therefrom, that have manifestly changed over time?
Precisely.
Here is an article[0] explaining papal infallibility that touches on some of these things in greater detail for those interested.
[0] http://edwardfeser.blogspot.com/2015/11/papal-fallibility.ht...
> Catholicism teaches that Divine Revelation is God's Self-Revelation and therefore can't change because God can't change.
The "God can't change" part seems a bit above our paygrade, no?
Not to mention: Who are we to say that God wouldn't reveal things to us gradually — and maybe in a changing way?
EXAMPLE: We still teach our kids that the sun rises in the east and sets in the west. Later, we refine the teachings.
This misunderstands the theology and metaphysics very profoundly.
The immutability of God is a necessary theological conclusion. If God changes, then He isn't God, by definition. It would be a metaphysical absurdity. Change presupposes imperfection and, therefore the potential for perfection, i.e., full actualization, but God as the Ipsum Esse Subsistens, is pure act with no potential left to actualize. God is fully dynamic, but this is quite different from change. He may appear to change from our temporal perspective as events are distributed in time, but from an eternal perspective, all is actualized, "simultaneous", so to speak.
W.r.t. gradual revelation, that is exactly what Scripture is a record of. A Catholic reading will demonstrate that revelation is in the business of slowly revealing to Man who God is (at least that which cannot be known through unaided reason; quite a bit can be known through reason alone), preparing him for the culmination of public revelation in the Incarnation of the Logos, something foreshadowed in the Old Testament. And furthermore, the Catholic Church recognizes the development of doctrine, which you could call a refinement and deepening of understanding of what has been revealed. I like the analogy to mathematics, even if it is imperfect: all the theorems that follow from a set of axioms are in a sense already in the axioms, and so mathematics is in the business of unpacking them.
However, this gradual revelation and development of doctrine, in order to be authentic, cannot contradict what was known previously, at least to a certain accuracy, if not precision. Of course, here is where people can get tripped up by analogical devices and literal-mindedness. Scripture is written using the idioms, paradigms, and language of the people who wrote it and for whom it was written. That means that some of the language may not agree with strict scientific descriptions of the 21st century. However, when that does occur, you will note that the sense is not the reference: when the Bible speaks of the sun rising in the east and setting in the west in order to communicate some theological truth, it is not making astronomical claims about the sun and the earth. It is using this language as instruments to communicate something, often by analogy. In fact, analogy is essential to theology, something captured in the concept of the analogia entis. Univocal or equivocal approaches to the subject of God have been the source of numerous heresies.
> The immutability of God is a necessary theological conclusion. If God changes, then He isn't God, by definition. It would be a metaphysical absurdity.
Is that so? Just because some people can't conceive of a mutable God, it doesn't mean it's impossible by definition. (Quantum mechanics was equally "inconceivable," until it wasn't.)
For the sake of argument, let's assume that God exists. Of course it's not our place to proclaim that God does change — that's above our paygrade, too. But to purport to categorically rule out the possibility is not just Dunning-Kruger arrogance, it's blasphemy.
Our discussion brings to mind chapter 38 of the Book of Job. We can summarize it (profanely) as God's saying to Job, in essence, "Who the f*ck are you to question me?"
https://www.biblegateway.com/passage/?search=Job%2038&versio...
It is, actually, necessary that God can't change. It is not _solely_ an article of Faith, but it's additionally something that someone without the light of Faith can know, although some pretty abstract thinking is required.
Most people think of the God of monotheism as a kind of super-angel. They think of Him as omnipotent, eternal, etc etc, but still something that exists in the same way that everything else exists. We say of a stone, a plant, a human being or an angel "it exists", and therefore, they think, we can say the same about God. This is the wrong way of thinking about Him, and it causes a lot of confusion (and it allows the Dawkinistas to put forth puerile arguments like "one god fewer"). It makes existence out to be something that God has, and therefore something that is, in itself, independent of Him. And if something is independent of God, then it would be higher than He is, and be something that He relied on, and that would mean He wouldn't be God.
It is instead much better to say that God is Being, and that everything else exists only in a derivative way. Everything else has being, but God is Being.
Pantheists and other monists argue that the universe itself is being, and that it can't ultimately change (the appearance of change is an illusion, they say). Their argument, to summarize horribly, is that anything other than being is non-being, and non-being can't do anything, since it doesn't exist. An acorn can't change into a tree, because that would imply that prior to the change the tree "is not", and that which is not can do nothing. The tree must therefore have always existed. Thus all change is an illusion.
They're mistaken insofar as they're talking about the visible universe -- change is absolutely real -- but what they say is roughly true for God. He can't change, because there is nothing that is Being apart from Him. Everything outside Him exists only derivitavely. This doesn't imply pantheism, because the things outside Him have real existence, but it is a kind of lesser existence.
A rough analogy: Light can't be dark. Other things can share in light without actually being light (noun), but they can't make light be dark. God is Being, and other things can share in his being but can't make Him non-being. Any change in Him would involve His going in some way from non-being to being. But non-being can't do anything, or become being. This is a very rough sketch of why God is immutable. This stuff requires some seriously abstract and non-quantitative thinking and isn't easy.
Job 38 doesn't imply that we can know nothing about God, only that we can't fully comprehend Him.