'Now concerning things sacrificed to idols.'
Paul here indicates by 'now concerning' that he is dealing with the second main question raised by the Corinthians through their visiting party (compare 1 Corinthians 7:1), the question of things sacrificed to idols.
'We know that we all have knowledge. Knowledge puffs up, but love edifies.'
It would seem that many Corinthian Christians were claiming that their superior knowledge as Christians meant that to them idols were nothing. Nor therefore was meat offered to them of any significance. Thus they could partake of it whenever, and wherever they liked, whether in Temples or at home, because they had 'knowledge'. They were in the know. They disregarded idols.
Paul accepts that such knowledge is common to Christians, but points out that greater than knowledge is love (1 Corinthians 13:11-13). He too knew that idols were nothing. But having such knowledge alone can make a man puffed up. What is more important is the approach of love, love to others who might not have that full knowledge. Love will make a man what he should be, and make him behave as he should. It is that which edifies him, feeds him and builds him up. We must view all things firstly from the viewpoint of love, of consideration for others and what effect our behaviour might have on them.
This applies to all knowledge of God. It is good to be strong in doctrine, or in 'spiritual knowledge', but not if we are not strong in love, love for God and love for our fellow-Christians. Being strong in love is the first essential and should begin before we become strong in doctrine. It is the distinctive feature that binds us all together. It is the evidence of what we are. 'He who does not love does not know God, for God is love' (1 John 4:8). Love is especially expressed in showing consideration to others (see chapter 13). It is the evidence that we are 'known of God'.