Let not then your good - That which you esteem to be right, and which may be right in itself. You are not bound by the ceremonial law. You are free from the yoke of bondage This freedom you esteem to be a good - a favor - a high privilege. And so it is; but you should not make such a use of it as to do injury to others.
Be evil spoken of - Greek, Be blasphemed. Do not so use your Christian liberty as to give occasion for railing and unkind remarks from your brethren, so as to produce contention and strife, and thus to give rise to evil reports among the wicked about the tendency of the Christian religion, as if it were adapted only to promote controversy. How much strife would have been avoided if all Christians had regarded this plain rule. In relation to dress, and rites, and ceremonies in the church, we may be conscious that we are right; but an obstinate adherence to them may only give rise to contention and angry discussions, and to evil reports among men, of the tendency of religion. In such a case we should yield our private, unimportant personal indulgence to the good of the cause of religion and of peace.

Let not then your good be evil spoken of - Do not make such a use of your Christian liberty as to subject the Gospel itself to reproach. Whatsoever you do, do it in such a manner, spirit, and time, as to make it productive of the greatest possible good. There are many who have such an unhappy method of doing their good acts, as not only to do little or no good by them, but a great deal of evil. It requires much prudence and watchfulness to find out the proper time of performing even a good action.

(16) Let not then your good be evil spoken of:
(16) Another argument: because by this means evil is spoken of the liberty of the gospel, as though it opens the way to attempt anything whatever, and gives us boldness to do all things.

Let not then your good be evil spoken of. The Vulgate Latin reads it, "our good", and so the Syriac version; the sense is the same, and to be understood either of the Gospel in general, which is good in its author, matter, effects, and consequences; is good tidings of good things, and which might be blasphemed by the men of the world, on account of the divisions and contentions among the professors of it, about such little trivial things, as eating this or the other sort of food; and therefore care should be taken, that it be not evil spoken of through such conduct: or else the doctrine of Christian liberty in particular, which is a good thing; Christ has procured it, and bestows it upon his people; it is a valuable blessing in itself, and is attended and followed with many considerable privileges and immunities; but may be evil spoken of by those, who do not so well understand it, through an imprudent use of it by those who do; and who therefore should guard against any reproach that may be cast upon it; and rather than this should be the case, forego the use of it, in things of an indifferent nature; see 1-Corinthians 10:30; so that this is another of the apostle's reasons, why though nothing is of itself unclean, yet it should be abstained from on account of others.

Let not then your good--that is, this liberty of yours as to Jewish meats and days, well founded though it be.
be evil spoken of--for the evil it does to others.

Let not then your good be evil spoken of. You have greater knowledge than these weak brethren, and know that "nothing is unclean." That is "good." But if you sternly insist on your right to do what the weak regard as sinful, your "good" will be evil spoken of.
For the kingdom of God. Christ's dominion; the church visibly; personally, his sway over your soul. This does not depend on meat and drink. It rises higher than food questions. Personally, its essence is not in external things. It consists of righteousness. Justification; the forgiveness of sins.
Peace. Reconciliation to God, and peace of soul as the result.
Joy in the Holy Ghost. The rejoicing of those who walk not after the flesh, but after the Spirit. Seek these rather than to eat and drink what you will.

Let not then your good and lawful liberty be evil spoken of - By being offensive to others.