The apostle instructed those who ate such food with a clear conscience not to despise the weakness of those who abstained…. And he told the weak not to condemn as polluted those who consumed such meat and wine…. For the strong insisted on despising the weak, and the weak did not hesitate to condemn the strong.
Paul wanted to keep the balance, by which scandals are avoided, between those who fast on Saturday and those who do not, so that the one who eats would not despise the one who does not eat, and the one who fasts would not judge the one who eats.
"Let him who eateth, not despise him who eateth not; and let him who eateth not, not judge him who eateth.".
"Qui "itaque "non comedit, comedentem ne spernat. Qui autem comedit, eum qui non comedit non judicet: Deus enim ipsum accepit."
We are not to abstain completely from different kinds of food but only not to be preoccupied with them. We are to eat what is set before us, as a Christian should, out of respect to our host.
God hath taken him to him, that eats of any meats; he accounts him his servant, and will reward him as such.
God is able to make him stand, and will justify him before his tribunal. (Witham)
Paul does not say that the one who eats should simply ignore the one who abstains, nor does he suggest that the latter should not be blamed and put right. All he is saying is that the stronger ones should not look down on the weak or be contemptuous of them. Likewise, those who abstain are not to pass judgment on those who eat. For just as the strong mocked the weak, claiming that they had no faith, that they were not really saved and that they were Judaizers, so the others thought that the strong ones were lawbreakers and gluttonous. Since these were probably mostly Gentiles, Paul adds that God has welcomed them.