I thank Dr. William Tighe for sending a link to an essay by the English Orthodox scholar, David J. Melling, who died in 2004. This paragraph seemed particularly worth taking to heart:
Progress in extricating ourselves from the bad habit of schism involves
a reappraisal of what is central to our Christian heritage and what is
transitory and peripheral, what is essential and what is merely a
matter of cultural tradition. When we return to the heart and centre of
our faith, we find ourselves together in Christ. If we lose the living
awareness of our oneness in Christ and identify ourselves simply in
terms of a particular community’s history and interests, we find a
chasm yawning at our feet.
It is gratifying to hear these words from a highly-regarded Orthodox authority. While Orthodoxy rightly emphasizes the unity of all things that pertain to the faith, Melling did not believe that every "connectable" is a vital part of the living Whole, and thought that at least some of what is regarded as such is (shall we say merely?) part of "a particular community's history and interests."
The temptation to elevate "what is merely a matter of cultural tradition" to canonical status bedevils every Christian community. This is why a positive conception of something like "mere Christianity" is not only logically necessary for tempering our senses of proportion, but more fundamentally, intuited by all those whose minds are disciplined by the love and knowledge of Christ. Please God to raise up leaders for the churches that are as zealous for the center of our faith as they are competent and willing to recognize what is transitory and peripheral.
I recommend the entire essay.