Having reminded us that our calling is to keep the unity of the Spirit in the bond of peace, Paul in Ephesians 4:4 tells us that "There is one body, and one Spirit, even as ye are called in one hope of your calling."
Here is a truth which we must maintain. Christ has only one body, that is, one church, wherein one Spirit works one hope in the members of that one church. It often does not look that way to our fleshly eyes. There are thousands upon thousands of congregations, and hundreds upon hundreds of different denominations with different names and doctrines. Are all one body? Are they all the same one body of Christ with the same Spirit?
All the elect children of God belong to that one body. And they are elect only if the Spirit has worked in them the one truth and the one and only true hope. The one Spirit speaks the one truth concerning Christ and His cross. Any church maintaining a false doctrine about Christ and His work of salvation is not part of the body of Christ. Satan works in churches as well as in the world. In some churches there is not the Spirit of Christ working faith and hope; but that evil spirit, the devil, is presenting the lie. Paul tells us this in Philippians 3:2 . In such churches we may not keep our membership. We must come out from among them and be a separate people ( II Cor. 6:17 ). Thus also the apostles called the believers away from the Jewish leaders that denied Christ and fought against His church. Paul himself was in prison because of the doctrines and false hope of those leaders of the Jews.
Our calling is to "keep the unity of the Spirit" (v. 3). And we must belong to a church wherein the Spirit, through the human servant, presents the truth concerning peace with God through Christ, not through works man performs. We must teach and believe that by His Spirit Christ must even give us the desire for salvation, and that giving us that desire He has already begun salvation in us.
Read: Romans 12 .
"To be at peace with the world, the flesh and the devil, is to be at enmity with God, and in the broad way that leadeth to destruction. We have no choice or option. We must either fight or be lost." J.C. Ryle