Yes, but teachings of churches can also be stable for periods of time long enough to be relevant for this discussion (at least in principle). I don't know whether the original article was written with this in mind, but I understood #6 to refer to any such long-standing tradition. Clearly no religious group nowadays (or in the last couple millenniums, for that matter) espouses Biblical teachings without thick layers of traditional interpretation, whether they admit it or not. So insofar as the question is interesting at all, it should be asked about these traditional interpretations, not the raw Biblical text.

(Also, while documents can remain unchanged for arbitrary periods of time in the sense of containing the same series of writing symbols, their interpretations will inevitably change even if the greatest efforts are made to interpret them with maximal literalism or originalism. Consider, for example, that a text written in a living language will, in some centuries, become an archaic document undecipherable without special linguistic and historical training, which by the very nature of things requires some nontrivial interpretation to extract any meaning out of it. In this situation, I don't think it's meaningful to talk about the document remaining "unchanged" in any practically relevant sense.)