Idols

 Therefore, as to the eating of food offered to idols, we know that “an idol has no real existence,” and that “there is no God but one.”
1 Corinthians 8:4 ESV
https://bible.com/bible/59/1co.8.4.ESV

We could read this verse in isolation and think that we could happily eat halal food for example. If we read in context however, we might have to think twice. Although food sacrificed to idols isn't harmful in and of itself, we still have to be mindful of those who are wary of it.

False gods might be nonexistent, but converts from false religions aren't. They might be uncomfortable eating food sacrificed to their old idols. If so, they shouldn't be obliged to eat it.

In ancient times, as in some places of worship nowadays, food was often served as part of religious rituals. The food itself might not be the problem, but going along with false religious rituals is questionable. This is especially insofar as it might upset people who have been saved out of such religions.

The message on food sacrificed to idols seems to be, if in doubt, avoid. If your brother or sister is going to be upset by it, avoid it. If your own conscience troubles you about it, avoid it.

'Lord God, we know that what really matters is faith in You, not what food we eat. Yet please help us not to sin against our own consciences, or those of our brethren. In Jesus' name, amen'