Rom 14:20

“"It is good, then, neither to eat flesh nor to drink wine," as both he and the Pythagoreans acknowledge. For this is rather characteristic of a beast; and the fumes arising from them being dense, darken the soul. If one partakes of them, he does not sin. Only let him partake temperately, not dependent on them, nor gaping after fine fare. For a voice will whisper to him, saying, "Destroy not the work of God for the sake of food."”

“Giving this name to the salvation of a brother, and adding greatly to the fears, and showing that he is doing the opposite of that he desires. For thou, he says, art so far from building up as thou intendest, that thou dost even destroy, and that a building too not of man but of God, and not for any great end either, but for a trivial thing. For it was "for meat," he says. Then lest so many indulgences should confirm the weaker brother in his misconception, he again becomes doctrinal, as follows, "All things indeed are pure, but it is evil for that man who eateth with offence." Who does it, that is, with a bad conscience. And so if you should force him, and he should eat, there would be nothing gained. For it is not the eating that maketh unclean, but the intention with which a man eats. If then thou dost not set that aright, thou hast done all to no purpose, and hast made things worse: for thinking a thing unclean is not so bad as tasting it when one thinks it unclean. Here then you are committing two errors, one by increasing his prejudice through your quarrelsomeness, and another by getting him to taste of what is unclean. And so, as long as you do not persuade him, do not force him.”

“He calls the salvation of a brother the work of God. Therefore, do not destroy that which was acquired for him by God, and moreover for the sake of food, that is, by an unwillingness to abstain from pork, in order to gain benefit for yourself. Having made a strict prohibition to the perfect one, he feared lest the weak one be confirmed in evil thoughts. Therefore he again turns to the doctrine and says that all things are clean, but it is bad for the one who eats with a bad conscience and after having been scandalized. For the imperfect one, who considers pork unclean, if he eats it under compulsion, suffers greater harm. Therefore you must first teach him that all things are clean.”

“Then when he says, destroy not the work of God for food, he presents the fourth argument, which is taken from our reverence for God's works, to which we owe this reverence in the sense that what God does we should not destroy for some bodily convenience: And this is what he says: for food, which is used by the body, destroy not the work of God. This, of course, does not mean just any work of God. For all the things which serve as man's food are God's works, as the produce of the earth and the flesh of animals, which have been granted to man for food, as it says in Genesis (Gen 1:29; 9:3). It means the work of grace which he works in us in a special way: God is at work in you, both to will and to work for his good pleasure (Phil 2:13). Therefore, we should not for the sake of food destroy this work of God in our neighbor, as they seemed to do who disturbed and placed stumbling blocks before the brethren by eating all foods without distinction. After presenting a reason to show that we should not set a stumbling block before our neighbor by eating all foods indiscriminately, the Apostle now shows how certain foods can be clean and unclean. In regard to this he does two things. First, he states which things are clean of their very nature, saying: all things indeed, which can pertain to man's food are clean, namely, of its very nature, because of its very nature it does not have the power to defile a man's soul, as it says in Matthew: not what goes into the mouth defiles a man (Matt 15:11); and in 1 Timothy: everything created by God is good (1 Tim 4:4). But certain things were declared unclean under the law not of their nature but by reason of what they signified, as is clear in Leviticus 11:2 et seq. But Christ even removed this uncleanness by fulfilling the figures of the old law. Hence it was said to Peter: what God has cleansed, you must not call common, i.e., unclean (Acts 10:15). Second, when he says, but it is evil for that man, he shows how some food can become unclean for a man, namely, it stains his soul to eat it; and this in two ways: first, when a person by eating all food indiscriminately puts a stumbling block before his neighbor; second, when he eats food contrary to his conscience, at blessed is he who condemns not. In regard to the first he does three things: first, he shows what is evil in taking food, saying: Although all things are by their nature clean, but it is evil for that man who eats a certain food with offense, i.e., with confusion and scandal to neighbor: woe to the world for stumbling blocks (Matt 18:7).”