Symbolism, Imagery, Allegory
Anyone who's ever had a broken foot knows it's pretty tough to get around without the help of that appendage. We take our bodies for granted when they're working well, but when something goes wrong, we see how much every single bit of ourselves helps us function. The same is true for the Christian community. At least according to Paul.
We Are One Body
Paul uses the metaphor of a person's physical body to describe the way that Christians all belong together:
For just as the body is one and has many members, and all the members of the body, though many, are one body, so it is with Christ […] Indeed, the body does not consist of one member but of many. If the foot would say, "Because I am not a hand, I do not belong to the body," that would not make it any less a part of the body. And if the ear would say, "Because I am not an eye, I do not belong to the body," that would not make it any less a part of the body […] But God has so arranged the body, giving the greater honor to the inferior member, that there may be no dissension within the body, but the members may have the same care for one another. If one member suffers, all suffer together with it; if one member is honored, all rejoice together with it. Now you are the body of Christ and individually members of it. (1 Corinthians 12:13-16, 18, 24-27)
Basically, Paul is saying that Christians are all like different parts that make up one body. They each have to play their part in order to keep this thing going. Even body parts no one cares about (pinky toe—we're looking at you), can turn out to be vitally important. (Ever try walking with a broken pinky toe? Ouch!)
It Does a Body Good
So Paul thinks we're all part of one big body, right? Then it's no surprise that he thinks that what we do with our bodies matters:
The body is meant not for fornication but for the Lord, and the Lord for the body. And God raised the Lord and will also raise us by his power. Do you not know that your bodies are members of Christ? Should I therefore take the members of Christ and make them members of a prostitute? Never! Do you not know that whoever is united to a prostitute becomes one body with her? For it is said, "The two shall be one flesh." But anyone united to the Lord becomes one spirit with him. Shun fornication! Every sin that a person commits is outside the body; but the fornicator sins against the body itself. Or do you not know that your body is a temple of the Holy Spirit within you, which you have from God, and that you are not your own? For you were bought with a price; therefore glorify God in your body. (1 Corinthians 6:13-20)
No fornicating, you hear? Paul is countering a Greek thought here—the idea that the soul is the best, most lovely part of you, and that the body is nothing special at all. If the body's just gonna die, then who cares if you hop into bed with a bunch of people you're not married to?
God does, apparently.
Not only do the actions of your body affect who you are as a person—when you "unite" with someone you become them, gross—it affects the whole body of Christ. This is just a fancy way of saying that things we do matter not just to ourselves, but to others. No body is an island. Literally.
Rock That Body
Okay, that all makes sense. But there's one idea in there that's caused some debate over the years: Paul calls individual Christians members of the body of Christ. What does he means by that?
Well, it's hard to say. Some people think that it means people become a part of Jesus through their belief in him. Others think it only refers to the church and that you have to be a member of a specific Christian church in order to be part of Christ's official body. There are lots of different interpretations. It just depends which member of the clergy you ask.
What's clear is that Paul wants to say that we're all related to each other and all in this together. Peace, love, and fully-functioning body parts for all.