The Greek word for a household is oikos. It's the word the New Testament uses for the church more than any other: the house of God, which is the church of the living God (1 Timothy 3:15); whose house are we (Hebrews 3:6); a spiritual house (1 Peter 2:5); the household of God (Ephesians 2:19).
Three words are built on it that you already know. Oikonomia, household management, is where our word economy comes from. In the New Testament every member is called an oikonomos, a steward: as every man hath received the gift, even so minister the same one to another, as good stewards of the manifold grace of God (1 Peter 4:10). Oikodome means house-building, or edification, the stated purpose of the assembly (1 Corinthians 14:26). And oikologia, the study of the household, is ecology.
That last word was coined deliberately. When the biologist Ernst Haeckel named the new science in the 1860s he built it on oikos on purpose, following Linnaeus's older phrase oeconomia naturae, the household management of nature. When Arthur Tansley coined ecosystem seventy years later, he used the same root.
So the science that studies how living systems hold together and the New Testament's most frequent word for the church share a root and a concept, the idea of a household in which many different parts are managed into one functioning whole. For a century and a half the science has been finding out what such a household requires. Its findings are 1 Corinthians 12, arrived at by people counting starfish.
The parts that seem least necessary hold up the whole
In the 1960s an ecologist named Robert Paine went down to a stretch of rocky Pacific shore and removed the starfish. He took that one species and nothing else, throwing them back into the sea by hand, repeatedly, for years. A control section was left alone.
The section without starfish collapsed into sameness rather than emptiness. The mussels the starfish had been eating spread across the rock and crowded out everything else. Within a few years the number of species had roughly halved. With the one predator that kept the mussels in check gone, everything connected to that balance went too.
Paine's term for it was a keystone species, meaning a part whose effect on the whole is out of all proportion to its abundance and whose importance is invisible until it's removed.
Set the starfish beside the text.
Nay, much more those members of the body, which seem to be more feeble, are necessary. (1 Corinthians 12:22)
Seem to be more feeble. Are necessary. On that shore the starfish was neither the most numerous animal nor the most visible. Nobody knew it was a keystone, because you don't find out what a keystone holds up until you take it out.
The same pattern runs through the living world in its least honored members. The decomposers are the fungi, bacteria and small animals that eat what's dead. Nothing in an ecosystem is less regarded, and nothing is more necessary, because without them nutrients don't cycle and the whole system starves on its own waste. Darwin's last book was about earthworms; he calculated that the worms of England turn over all of its topsoil, unseen, and that the fertility of the land depends on an animal nobody thought about.
Our uncomely parts have more abundant comeliness (12:23). The soil says the same thing the design does.
Remove one part and everything connected to it changes
Sea otters eat sea urchins. Sea urchins eat kelp. When the otters were hunted out of long stretches of coast, the urchins multiplied and grazed the kelp forests down to bare rock. Where the otters returned, the urchins fell, the forests came back, and with them the fish and everything that lived in the fish.
Ecologists call this a trophic cascade. Remove one part and the effect spreads through everything connected to it, in directions nobody would have predicted from looking at the part alone.
And whether one member suffer, all the members suffer with it. (1 Corinthians 12:26)
It would be easy to hear sentiment in that verse, but in a connected system it describes a mechanism. The kelp suffered without caring anything for the otters. It was connected to them by two links, and the links carried the loss.
In a congregation, the absence of a part is never local. When a person stops coming, the hole they leave is much bigger than one person. It's the size of everything that ran through them, including the people they were the link to, the information only they carried and the check they provided on someone else. Nobody sees the cascade, because nobody was mapping the links.
Many different parts capture more, and survive what one cannot
For three decades ecologists in Minnesota have run an experiment in which plots of prairie are planted with one, two, four, eight or sixteen species and then measured. The plots with more species produce more and are more stable; in drought years the diverse plots lost far less than the monocultures.
Two mechanisms explain it. Complementarity means that different species use different resources, at different depths and times, so the whole community captures what no single species could reach. The insurance effect comes from different species responding differently to the same shock. When drought comes, some fail and some don't, and the survivors carry the system through.
If the whole body were an eye, where were the hearing? If the whole were hearing, where were the smelling? (1 Corinthians 12:17)
Those rhetorical questions describe complementarity. A body of one function captures only what that function can reach.
The same research answers the efficiency argument that keeps the modern church in its current shape. A monoculture is the most productive arrangement in a good year and the most fragile in a bad one. A field of one species gives a high yield, but it depends on constant external input and is vulnerable to a single pathogen, because there's nothing in the field the pathogen can't reach. The potato famine was a monoculture meeting one blight.
Describe the modern congregation in those terms. A professional is its one functioning part, doing the teaching, the counseling, the visiting and the leading. In a good year the yield is high. The arrangement depends on constant external input, in this case money, and it's vulnerable to a single failure, because everything runs through one organism. When he falls, or leaves, or burns out, the congregation discovers, as a monoculture does, that there was nothing else in the field.
Presence is not function
Ecologists call a species functionally extinct when it still exists but no longer does its job. The animal is there somewhere, but there are too few of them, or they're too scattered or too sick, to perform the role the system depended on, such as dispersing seeds, controlling grazers or cycling nutrients. With the species present and the function gone, the system responds exactly as if the species were absent.
The verse that governs this is in Ephesians.
From whom the whole body fitly joined together and compacted by that which every joint supplieth, according to the effectual working in the measure of every part, maketh increase of the body unto the edifying of itself in love. (Ephesians 4:16)
The body grows according to the effectual working in the measure of every part. The verse measures each part by its working and says nothing about its presence. And the goal the verse names, near its end, is oikodome, house-building. The household grows by building itself up through the working of every part.
So the design makes a stronger claim than "everyone belongs." Everyone functions, or the whole doesn't grow. A member who is present and does nothing is functionally extinct as far as the body is concerned. The body suffers the loss exactly as if the member were gone, and doesn't know why, because the member is visibly there.
Described in ecological terms, the passive congregation has four hundred people present and a dozen functioning. Because it has confused occupancy with function, which no ecosystem ever does, it can't understand why it isn't growing when the pews are full.
The first vocation
The first task given to a human being was ecological: And the LORD God took the man, and put him into the garden of Eden to dress it and to keep it (Genesis 2:15). To dress and keep is to cultivate and guard a household of living things.
The household of God is that garden. The honour inversion (upon these we bestow more abundant honour) is how it's kept, with the body deliberately protecting its keystones against the ranking that would let them disappear. The one-anothers are the links through which the whole holds together.
Ask of your congregation: who are the keystones nobody has named? What cascade did the last departure set off? Where is the monoculture, and what happens when the one crop fails? And who is present but functionally extinct, and what would it take for them to work again?
The first gardener was told to keep the garden. That instruction has never been withdrawn.