4 There is one body and one Spirit, just as you were called in one hope of your calling;
Having urged unity among believers in the previous verse, verses four through six set forth seven components that make for unity. Paul designated each by the word “one.”
This unity revolves around the Trinity. The fourth verse focuses on the unity of the Holy Spirit, verse five on the Son, and verse six on the Father.
4 There is one body
“One body” here is the universal church. The church is a spiritual organism (1:23; cf. 1 Co 12:13). All believers are in this spiritual body because they are “in Christ.” This is not an organization but an organism, a shared life together. There is a common life regardless of factors that might cause dissension. This is the church’s fundamental unity.
and one Spirit,
“One Spirit” is the Holy Spirit indwelling the church (2:22). He is the unifying force of the body of Christ. Believers themselves are temples of the Holy Spirit (1 Co 3:16-17). Collectively they are one temple in the Lord (Eph 2:21-22). The Father gave the Spirit as a pledge for keeping our salvation (Eph 1:14). He is, therefore, our guarantee to have eternal life.
The power of the church does not come from anything other than the Holy Spirit. It does not come from organizations, from numbers, or from political influence in society. The power of the church rests on the supernatural, the Holy Spirit (Zech 4:6).
The words “just as” indicate that believers are one body and have one Spirit because they have “one hope” in Christ. Our hope shows that we are one body.
you were called
Our calling is the framework for our walk with God.
in one hope of your calling;
All Christians have a common hope that began with their salvation. Hope is something that unites all Christians. We have a future together in Christ. “Hope” in the Greek indicates confidence. Unity flows from our “calling.”
Christians have a future together in Christ.
The church is to be catholic (universal). There is one body of believers in the universal church. The universal church includes any believer anywhere who trusts the blood of Christ for his salvation. There is no denomination in this church. Jew and Gentile hold the same status.
The church should function with corporate unity. Sin against the unity of the universal church is a sin against the Holy Spirit who indwells the church.