Now as touching things offered unto idols, we know that we all have knowledge. Knowledge puffeth up, but charity edifieth.
Though to those knowing that an idol has no existence, the question of eating idol-meats (referred to in the letter of the Corinthians, cf. 1 Corinthians 7:1) might seem unimportant, it is not so with some; and their infirmities should be respected. The portions of victims not offered on the altars belonged partly to the priests, partly to the offerers; and were eaten at feasts in the temples and in private houses, and were often sold in the markets; so that Christians were constantly tempted to receive them, which was forbidden (Numbers 25:2; Psalms 106:28). The apostles forbade it in their decree (Acts 15:1-41; Acts 21:1-40; Acts 25:1-27); but Paul here rests his precepts rather on his own independent apostolic authority.
We know that we all have knowledge. The Corinthians had referred to their "knowledge" (namely, of the indifference of meats, as in themselves having no sanctity or pollution). He replies, 'We are aware that we all have (speaking generally, dud so far as Christian theory goes: for in 1 Corinthians 8:7 he speaks of some who practically have not) this knowledge.'
Knowledge puffeth up - when without "love." Here a parenthesis begins: the main subject is resumed in the same words 1 Corinthians 8:4. "As concerning (touching) the eating," etc. 'Puffing up' pleases self. 'Edifying' benefits one's neighbour. Knowledge says, All things are lawful for me: Love adds, But all things do not edify (1 Corinthians 10:23; Romans 14:15).
Edifieth - builds up the spiritual temple (1 Corinthians 3:9; 1 Corinthians 6:19).