Among the various camps in the debate between creation and evolution is a set of ideas called intelligent design (ID). A key part of ID is “irreducible complexity,” a term that comes from the book Darwin’s Black Box, by Lehigh professor Michael Behe.
In short, irreducible complexity argues that evolution by chance, without an intelligent designer driving it, is unreasonable because the multiple systems in a complex organism like a human body – circulatory, digestive, endocrine, muscular, respiratory, and so on – are all interdependent on each other. The circulatory system alone, with the heart pumping blood through an elaborate system of arteries and veins, is difficult to imagine developing by chance occurrence, but a chance evolution of that system alongside all the other parts it is dependent on is even more far-fetched. All systems evolving together in lockstep without failing is a much more difficult problem to explain scientifically without a Creator. The circulatory system takes what the respiratory and digestive systems take in and deliver it to the other systems that use it. Without the other parts, it has no function and cannot survive and further evolve.
However, my intent here is not to prove intelligent design, but to consider the apostle Paul’s words about the church as the body of Christ. In 1 Corinthians 12:12, he wrote: “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.” He continues that no part of the body can say it is not a part of the body because it has a different function than another part (1 Cor. 12:15-16), and also that no part of the body can say it doesn’t need all of the other parts (1 Cor. 12:21). Those who are in Christ Jesus cannot be divided.
Paul follows his description of the body with 1 Corinthians 13, a powerful statement on the supremacy of love, and in context a gentle rebuke to the idea that a body can survive as individual, unrelated units. In a human body, any part can only survive by serving the other parts. Even an organ as incredibly complex and important as a heart cannot survive if it decided to pump blood only for itself. Where would it get its nutrients? How would it flee from danger? As Paul wrote: “If the whole body were an eye, where would be the sense of hearing? If the whole body were an ear, where would be the sense of smell?” (1 Cor. 12:17). Even an organ as important as the heart is useless in isolation. It gets its very life and purpose by what it does for the body.
As Jesus said to His disciples in John 13:34-35 – “A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another. By this all people will know that you are my disciples, if you have love for one another.”
As the song says, they will know we are Christians by our love, and the church Jesus came to build is irreducibly complex. There is no appendix in the church, which is the body of Christ.