en_tn/rom/12/05.md

are individually parts of each other

Paul speaks of the believers as if God had physically joined them together like the parts of the human body. You can translate this in an active form. Alternate translation: "God has joined each believer together with all other believers" (See: rc://en/ta/man/translate/figs-metaphor and rc://en/ta/man/translate/figs-activepassive)