That's the question Paul wrestles with in these chapters (specifically 8-10). They wondered about meat sacrificed to idols. Paul's basic argument goes something like this...
- There are no real idols, so food sacrificed to them is just food (8.4ff).
- Behind the idolatry, though, lie demons - so you want to be careful with the spiritual entities that undergird the physical idols (10.20).
- Don't mess with your own conscience - that's a bad idea because it hardens you against other promptings of the Spirit (8.7).
- Don't mess with another's conscience because that's unloving (8.11-13).
And here, for me, is the modern day application: I can focus on my rights and lose righteousness. I have rights. But exercising those rights at all times might very well harm others, which is unrighteous. And it's pretty clear what God would prefer.
But that's just me thinking thoughts...