John Calvin Commentary Romans 12:4

"For even as we have many members in one body, and all the members have not the same office:" — Romans 12:4 (ASV)

For as in one body, etc. The very thing which he had previously said of limiting the wisdom of each according to the measure of faith, he now confirms by a reference to the vocation of the faithful.

For we are called for this purpose: that we may unite together in one body, since Christ has ordained a fellowship and connection between the faithful similar to what exists between the members of the human body. And as people could not by themselves come together into such a union, he himself becomes the bond of this connection.

So then, just as it is with the human body, so it ought to be with the society of the faithful. By applying this analogy, he proves how necessary it is for each person to consider what is suitable to their own nature, capacity, and vocation.

But though this analogy has various parts, it is nevertheless to be primarily applied to our present subject as follows: just as the members of the same body have distinct offices, and all of them are distinct, for no member possesses all powers, nor does it appropriate to itself the offices of others; so God has distributed various gifts to us.

Through this diversity, he has determined the order that he intends to be observed among us. Therefore, everyone is to conduct themselves according to the measure of their capacity and not thrust themselves into what uniquely belongs to others. Nor should anyone seek to have all things for themselves; instead, they should be content with their lot and willingly abstain from usurping the offices of others.

However, when he explicitly points out the communion that is between us, he also intimates how much diligence everyone ought to show, so that they may contribute to the common good of the body according to the abilities they possess.