"Do I mean then that a sacrifice offered to an idol is anything, or that an idol is anything? No, but the sacrifices of pagans are offered to demons, not to God, and I do not want you to be participants with demons." NIV translation
Paul goes on to show us that any offering that is made and is not made to God is dealing with demons. The idols and the sacrifices mean nothing but they can draw people away from God.
"You cannot drink the cup of the Lord and the cup of demons too; you cannot have a part in both the Lord's table and the table of demons. Are we trying to arouse the Lord's jealousy? Are we stronger than he?" NIV translation
The concept of sharing a meal with someone is one of intimacy and so, Paul tells us that we cannot have an intimate relationship (dine with) the Lord and also with demons. He reminds us that God is a jealous God because of the fact that He loves us (see Zephaniah 1).
"'Everything is permissible' - but not everything is beneficial. 'Everything is permissible' - but not everything is constructive." NIV translation
Now that Paul has reminded us that Jesus has saved us, he goes on to tell us more about what that means. This salvation is freedom as we see that he says two times that "Everything is permissible". This is freedom from worry about our eternal home and we do not have to worry about breaking some rule and losing our place with Christ. It does not matter what you have done or will do because Jesus Christ has paid it all. But, Paul goes on to remind us that not everything is good for building us up in our walk with the Lord. We can do anything without fear of losing our salvation but there will be consequences for everything. One of the biggest problems with doing whatever we want is the distance that it brings between us and Christ.
"Nobody should seek his own good, but the good of others." NIV translation
Now, we are introduced to the reason for the restraint of our freedom. We see that, if we are in Christ, our focus shifts from self to others and the fact that our actions can have a big impact on those around us.