Ever wonder why old churches are built like the blueprint above? So that worship is modeled after the body of Christ!
The Church as "The Body of Christ" was a key Scripture for my becoming Catholic, it is a stumbling block for many Protestants, and it was interpreted by The Second Vatican Council's Dogmatic Constitution on The Church - Lumen Gentium. To fully appreciate this Scripture, we must consider the body of the Lord at the Crucifixion, the Resurrection, and The Ascension. The Church is this one body of Christ, now glorified and perfected.
The phrase "Body of Christ" is notably found in two of St. Paul's epistles, one to the Catholics at Colossae [Asia Minor], the others at Ephesus [Greece].
He is the head of the body, the church
...the head over all things for the church, which is his [Christ's] body, the fulness of him who fills all in all.
Think about your own head and body. Are you not all of it? Note that St. Paul is writing about The Church as The Body of Christ after the Ascension. Now consider the following:
Christ with The Church is the "whole Christ," just as my head and body together is the "whole me."
Therefore, Christ without The Church is a decapitated Christ, a dead head.
Therefore, The Church without Christ is a headless horseman, a decapitated corpse.
Therefore, The Church is visible just like Jesus' body is visible.
Therefore, The Church is one, just as Jesus' body is one.
Therefore, The Church is holy and glorified as a whole, because Jesus' glorified body is holy.
Why is it difficult to understand The Church as "The Body of Christ?" Because other "models of church" have already taken root in the Protestant mind. To evangelize better I present you with common weeds and how to pull them up by the root. Feel free to scroll to find the one that helps you.
"The Invisible Church vs. The Visible Church"
This is a Reformed, Calvinist, and Presbyterian position. It posits there is an "invisible" church and a visible one. "Bodies" by definition are visible, physical things. "Invisible" things are things like justice, mathematical lines, or doubleness. If The Church is two bodies, then so too is Jesus. Which one died for us on the cross then?
[See: Nestorianism, Substance Dualism, Gnosticism, Cartesianism]
"A church of the 'catholic' Tradition without being The Catholic Church"
This is an Anglican, Orthodox, and Methodist position. This idea holds to a "catholic tradition" which is intangible and can incarnate in many bodies. Jesus then is a ghost that decides to haunt various church bodies bringing them spiritual authority. If he is a ghost, then he is not his body. If he is not his body, then Jesus was never crucified, some shell of a body was. We're all damned.
[See: Gnosticism, Dualism, Cartesian mind-body gap, Soul-Body Divide]
The "Corrupt Church" replaced with The Community of True Believers
This is a Baptist, Evangelical, and Fundamentalist position. Because there are bad Christians the entire Church is bad. If my toe is purple does that mean all of me is purple? If a branch is dying does it follow the whole vine is dying? Christ is the vine, we are the branches. Just because a part has an attribute, doesn't mean the whole does. If Man's sins can ruin Christ's salvific plan, then Man is more powerful than Jesus. Thus Jesus can't be God. Therefore he was another mere mortal executed by The Romans. I guess Jesus is not Lord and Saviour.
[See: Arianism, Polytheism, Part-Whole Fallacy, Hasty Generalization, ]
"All Denominations are The Church."
This idea is common to almost all Protestant groups. Jesus is not a Body made up of members, but a Mega-Body made up of denominational bodies. So he's like a Monster or Hobbes' Leviathan or a Megazord, or something. He ain't human, so I guess humans weren't redeemed on the cross, something else was. I guess there will be no Resurrection or salvation for any humans. "Abandon all Hope, ye who enter here."
[See: Nestorianism, akin to Eutychianism, Part-Whole Fallacy]
"The Church was good but The Apostles or their predecessors immediately corrupted it - Church:"
This is a position taken by any Protestant who questions what their tie is to Jesus laying physical hands on The Apostles [not any disciples] and giving them authority to cast out demons, forgive sins, and to baptize. The idea purports that The Church was pure but corrupted after The Apostles. The tale then says The Early Church got to "insert-our-denomination's-practices-here," (e.g. charismatic worship, spontaneous prayer, snakehandling, rock concert worship, et al.). History only shows some modern churches are repeating early Church heresies - whoops - wrong team. If The Church corrupted and had to be reborn by "true believers," then the Body of Christ died again, after The Resurrection. On the contra, The Holy Scriptures say, "For we know that Christ being raised from the dead will never die again; death no longer has dominion over him" (Romans 6:9). It's quite presumptuous to think a few humans could succeed where the very throng and siegeworks of the infernal hosts have failed. If humans can wreck Jesus' plan, then I guess Jesus isn't God, and if he's not God, the cross did nothing for salvation. I guess we're still waiting on The Messiah?
[See: Arianism, Montanism, Gnosticism]
"The Body of Christ is a Metaphor and you're taking it too literally Church"
This idea says that the arguments above take the metaphor "too literally." This idea is a way to dodge the question. Typically they just back to "The Church" as "believers." This doesn't address the question of The Church as a whole. If I asked what a car is you couldn't say a pile of nuts and bolts and rubber tires. It has to be one thing that has all those parts. By the end you realize what's really being said here is "Yes, I agree The Church is The Body of Christ, but not in any way I can think of." Just restate the question, "What is The Church?" A second possibility is they return to "It's The Community" or "The People," and this is true, but it fails to see how Jesus' body had a divine nature dwelling in it. If that's all The Church is, then the Body of Christ is only human, and Jesus isn't God. Just another joker crucified among many. No salvation here.
[See: Arianism, Equivocation Fallacy, Whole-Parts Fallacy]
"I have a personal relationship with Jesus Christ so I don't need The Church"
This is the Evangelical or Non-denominational position of The Church par excellence. First off, "personal relationship with Jesus" is not Scriptural language. It was a secular phrase adopted by Protestant preachers to "be relevant."
A relationship tells us that two things are connected, whereas bodies tell us what things are. E.g., if I said, "The two cogwidgets have a relationship and made baby cogwidgets" you learn that the cogwidgets "related" in a way to reproduce, but you still don't know what "cogwidgets" even are. Therefore, answering the question about what the body of Christ is by talking about relations just doesn't answer the question. A relation is one category of being, bodies are a different category of being. Functionally then, this idea says that salvation is not from Christ's body, but from relating to a purely spiritual version of Jesus. The Son could have yelled down to us from the heavens, "Be in a relationship with me!" The Father sending Christ to die therefore is not only unnecessary for salvation, it is unfitting. The Father is a bloodthirsty god killing The Son for no reason. He is an evil god. Christ is the nice god, he relates to us. What logically follows is either polytheism or atheism. It's no wonder the communities that meet in these buildings have lights, guitars, and coffee, but never a cross. Pointing out these architectural anomalies can help make this point to friends, but be gentle.
[See: Categorical Error Fallacy, Gnosticism, Manicheanism, Dualism]
The Divine Element of The Church
The Church as "Body of Christ" signifies to us the Divine Element of The Church. Last week we spoke of the Human Element being present by The Church as "The People of God." Notice as the People The Church can be sinful in its members, but as The Body of Christ it cannot be sinful in its substance. It's perfection and holiness rests on Jesus, not Man.
(1) The Church is the Body of Christ
(2) The Body of Christ circumscribes both human and divine natures.
:. Therefore, The Church circumscribes both human and divine natures.
The Second Vatican Council states this quite succinctly:
But, the society structured with hierarchical organs and the Mystical Body of Christ, are not to be considered as two realities, nor are the visible assembly and the spiritual community, nor the earthly Church and the Church enriched with heavenly things; rather they form one complex reality which coalesces from a divine and a human element.
--Lumen Gentium: Dogmatic Constitution on The Church
Whatever we say about Jesus, we're saying about The Church. If Christ is the Sun, radiating glorious rays to the Cosmos, then The Church is the Moon, whose glory while dazzling is all due to her reflecting of the Sun's beams. Thus The Early Church often compared The Church to The Moon. In short there are three characteristics we can learn by the "The Church is The Body of Christ:"
One: one body with many human members
Visible: physical body manifested in people and political structure, but held together by the invisible Spirit
Holy: it is like Our Lord, incapable of decay, corruption, or death in its substance, but members may be cut off as with a vine