The image of the Church as the “body of Christ” is absent from the earliest Pauline epistles; it first appears in the first epistle to the Corinthians, in which St. Paul uses the image to dissuade the Corinthians from divisive and immoral behavior.
St. Paul begins by reminding the Corinthians that they were washed, sanctified and justified in the name of Jesus Christ and in the Spirit of God (1 Corinthians 6:11). For this reason, a Christian must preserve himself from immorality and impurity - “The body is not for sexual immorality but for the Lord, and the Lord for the body. And God both raised up the Lord and will also raise us up by His power. Do you not know that your bodies are members of Christ” (6:13-15)? Through baptism in the name of Christ, through the grace of the Holy Spirit, the Christian’s body becomes a member of the body of Christ (the same rationale for purity is applied to becoming a temple of the Spirit in 6:19-20).
In the second passage from 1 Corinthians (10:1-22) St. Paul develops a sacramental understanding of being a member of the body of Christ. The primary focus of the passage is Paul’s warning against partaking in fellowship meals at idol shrines. Christians are warned to shun the worship of idols (10:14), because - even though idols are not legitimate gods - an atmosphere of spiritual distortion is characteristic of idolatry (see Romans 1:18-32), and therefore such worship can make the individual a partner with demons (10:20-21). In contrast to the corrupting unity of such false worship, God provided the early Israelites with the “supernatural” food and drink of Christ (10:3-4); this supernatural food and drink prefigured the Eucharist to which St. Paul then moves.
Paul’s explanation of the membership of the Christian in the body of Christ is for the first time explicitly involves the Eucharist: “The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ? For we, though many, are one bread and one body; for we all partake of that one bread” (1 Corinthians 10:16-17). Partaking of the food and drink is to participate in the body and blood of Christ and in the unity of the Church.
The passages from 6:11-20 and 10:1-22 depict the Church as consisting of faithful individuals who are members of the Christ and temples of the Spirit; their unity is achieved in the sacrament of baptism and partaking of the Body of Christ. This culminates in the image of the body presented in 1 Corinthians 12, in which St. Paul emphasizes the unity of Christians in the body of Christ.
In 1 Corinthians 12:12 St. Paul emphasizes, “For as the body is one and has many members, but all the members of that one body, being many, are one body, so also is Christ.” In 6:15 St. Paul stated that are bodies are members of Christ; in this passage he goes further and explains that those who are individually united to Christ form one body. The allegory in 1 Corinthians 12:14-26 demonstrates the significance of this for the individual: the Holy Spirit Who sanctifies us in baptism, Who impels to proclaim that Christ is Lord, also provides us with gifts so that we can perform a special role in the body (12:4-6), just as physical organs and appendages perform vital bodily functions (Ibid.). The church offices of apostle, prophet, teacher, etc., therefore do not create distinctions between individual Christians (12:28-31): all are necessary within the one body, and there is therefore an inherent unity and equality between them. A similar message can be found in Romans 12:4-8, which St. Paul wrote during approximately the same period as 1 Corinthians.
In his later epistles St. Paul expanded on the image of the body of Christ by focusing on the head: Christ Himself. In his epistle to the Colossians St. Paul emphasizes the supremacy of Christ over cosmic powers (see also Romans 8:38-39), and thus His superiority to false religious groups that were troubling the church in Colossae. This context is vital to understanding Colossians 2:10, in which St. Paul states: “You are complete in Him, who is the head of all principality and power.”
Later in the same chapter, however, St. Paul directly addresses the Christ-Church relationship: “(Christ is) the Head, from whom all the body, nourished and knit together by joints and ligaments, grows with the increase that is from God” (Colossians 2:19). This passage is clearly related to the earlier statement in 1:17-18: “In Him all things consist. And He is the head of the body, the church.” In this phase in the development of Pauline theology mentioning the Christ-cosmos relationship is necessary for understanding the Christ-Church relationship: Christ is the victor over the elements of the cosmos that were binding humanity, and He therefore is the Head over the body (Church) whose joints (members) are resurrected in Him. This understanding is emphasized in the word “nourished” in 2:19. “Nourished” means to supply or minister; the victorious resurrected Christ supplies His Church with guidance and direction, and sustains it by His authority.
The theme of unity in Christ is fully developed in the epistle to the Ephesians. The authoritative element of the Christ-Church relationship is stated early in the epistle: “[God] put all things under His feet, and gave Him to be head over all things to the church, which is His body, the fullness of Him who fills all in all” (1:22-23). St. Paul exhorts the Ephesians to appreciate the greatness of the power of God that is working in their church (1:19).
Christ uses this authority to fill “all in all,” to unify the Church in Himself. Through His victory Christ “made us both [i.e., Jew and Gentile] one…so as to create in Himself one new man from the two, thus making peace, and that He might reconcile them both to God in one body through the cross” (Ephesians 2:14, 15-16). St. Paul reiterates: “There is one body and one Spirit, just as you were called in one hope of your calling; one Lord, one faith, one baptism; one God and Father of all, who is above all, and through all, and in you all” (4:4-6), and it is in dependence on Christ that the body is bonded and knit together (4:16).