Romans14chapter 14

Meat in a Roman city was hard to trust. Much of what reached the market had come from a temple, since animals were sacrificed there and the surplus sold, and Rome had no reliable kosher supply chain for ordinary buyers. A conscientious Jewish believer could avoid the whole problem by eating only vegetables — which is exactly the position Paul describes.

Wine had a parallel difficulty, since a portion was often poured out to a god before drinking.

The disagreement over days almost certainly involves the Sabbath and the Jewish festival calendar. For believers whose families had kept those days for generations, letting them go was not a small adjustment; for Gentile believers who had never kept them, insisting on them looked like adding requirements.

Underneath sits the recent expulsion and return. The group that stayed had set the customs; the group coming back had older ones. Paul refuses to legislate the answer and instead forbids two things: the strict despising the free, and the free judging the strict.