17. διὰ τοῦτο, Eph 6:13. Such being the need for watchfulness.
μὴ γίνεσθε ἄφρονες. Cf. Eph 5:7. ἄφρων is constant in the Wisdom literature for various Hebrew equivalents. It suggests the thought of moral recklessness. It is a characteristic of heathen society in 1Pe 2:15. For the distinction between σοφία, φρόνησις, σύνεσις see on Eph 1:8 and Eph 3:4.
ἀλλὰ συνίετε. The opposite to insensate recklessness is quick discernment of the signs of God’s Will. συνίετε is constantly used of the power of spiritual apprehension, the understanding of Parables, &c., Mat 13:10 ff., Mat 13:19 &c.
τί τὸ θέλημα τοῦ κυρίου. Cf. Rom 12:2; Col 1:9. This is another way of expressing the thought of Eph 5:10.