en_tn/eph/03/06.md

the Gentiles are fellow heirs and fellow members of the body and fellow sharers in the promise in Christ Jesus through the gospel

This statement is the hidden truth Paul was stating that was revealed to him and the apostles.

fellow members of the body

Paul continues to use the analogy of the physical body in describing the the believers in Christ.

For this I became a servant

"I am now serving God to spread the gospel" (see rc://en/ta/man/translate/figs-explicit)