Having laid out the big picture and also some of the smaller details in vv.1-3 Paul now gives a wonderful trinitarian teaching on unity in vv.4-6:
“There is one body and one Spirit, just as you too were called to the one hope of your calling, one Lord, one faith, one baptism, one God and Father of all, who is over all and through all and in all.”
Paul speaks of the true unity that believers have (one body and one Spirit). Unity between believers (one body) is found because they have the same one Spirit. One hundred pianos all tuned to the same fork automatically are in tune with one another, right?
Unity is found in our trinitarian Godhead (one Spirit…one Lord…One God and Father of all…) and in the singular hope of [our] calling. There is far more to unite us when we become born again believers in Jesus than divide us. Historical differences, cultural or linguistic differences, and even non-essential doctrinal differences pale into insignificance compared to the hope of [our] calling. Where Scripture is being correctly and properly handled and taught (2 Timothy 2.14-16) God will be glorified, the Lord will be magnified, and the Spirit will testify. This brings a unity that we cannot manufacture, and a unity that brings together people who are, on the surface, as different as can be.