The Apostle Paul
Romans 12:5BSB·traditional attribution

so in Christ we who are many are one body, and each member belongs to one another.

Matthew Henry Presbyterian @wholebiblehenry

We may observe here, according to the scheme mentioned in the contents, the apostle's exhortations, I. Concerning our duty to God, We see what is godliness. 1. It is to surrender ourselves to God, and so to lay a good foundation. We must first give our own selves unto the Lord, Co2 8:5. This is here pressed as the spring of all duty and obedience, Rom 12:1, Rom 12:2.

Commenting on Romans 12:1-21

John Gill Reformed Baptist @doctorgill

So we being many are one body in Christ,.... This is the application of the above simile. The chosen of God, the redeemed of Christ, and those that are justified by his righteousness, and sanctified by his Spirit; though they are but few in comparison of the men of the world, but considered in themselves are many, and yet make up but one body, the...

Albert Barnes Presbyterian @notesbybarnes

Verse 5. So we, being many. We who are Christians, and who are numerous as individuals. Are one body. Are united together, constituting one society or one people, mutually dependent, and having the same great interests at heart, though to be prompted by us according to our peculiar talents and opportunities.