John Calvin Commentary Romans 14:2

"One man hath faith to eat all things: but he that is weak eateth herbs." — Romans 14:2 (ASV)

Let him who believes, etc. What Erasmus has followed among the various readings I do not know; but he has mutilated this sentence, which, in Paul’s words, is complete. Instead of the relative article, he has improperly introduced alius — one, “One indeed believes,” etc. That I take the infinitive for an imperative should not seem unnatural or strained, for it is a very usual way of speaking for Paul.

He then calls those believers who were endowed with a fully satisfied conscience; he allowed these the use of all things without any difference. Meanwhile, the weak ate herbs and abstained from those things whose use he thought was not lawful.

If the common version is more approved, the meaning then will be — that it is not right for him who freely eats all things, believing them to be lawful, to require those who are still tender and weak in faith to walk by the same rule.

But to translate the word sick, as some have done, is absurd.