What does the "unity of the Spirit" mean in Ephesians 4?

What is the meaning of Ephesians 4:3?

"Endeavoring to keep the unity of the Spirit in the bond of peace" doesnt refer to a manmade unification, but to the unity of the one Body (verse 4) formed at Pentecost. If we recognize the distinction between the Church, the Body (of which there is only one), and the church of God (of which there are many, 1 Corinthians 11:16), we must conclude that groups of congregations do not form this unity. It was formed positionally by the Spirit at Pentecost; it is expressed practically in each assembly. The Body is not Gods testimony in this age; churches of God are (Revelation 2, 3), therefore each assembly displays this truth. Churches are united in their obedience to the Lord (1 Corinthians 11:16) and their accountability to Him (Revelation 2, 3), but each is distinct and complete in itself (Revelation 1:20; 1 Corinthians 14:23).

Paul often stresses unity within the assemblies he addresses. This may be a primary objective in Romans (see 12:4, 5) and Galatians (5:15, 25). The need for unity within the assembly runs through 1 Corinthians (eg., 1:12-24). In Ephesians, Paul declares that God established in the Body a unity between Jews and Gentiles (2:11-18). By their walk, believers maintain unity by living above their natural prejudices (4:25). We are responsible for right behavior toward all believers, but Paul here emphasizes behavior in the assembly because the assembly testifies to the truth of the one Body.

D. Oliver