The Blessed Effects of God’s Saving Grace (4:1–6:20)
Examples of pure living
So Paul wraps up this section with something of a summary:
Be very careful, then, how you live—not as unwise but as wise, 16 making the most of every opportunity, because the days are evil. 17Therefore do not be foolish, but understand what the Lord's will is.
“[Understanding! what the Lord’s will is” and living according to it—that is wisdom. To do otherwise would be “unwise” and “foolish,” a lapse back into darkness, a return to the pagan cesspool from which the Ephesians have just recently been rescued.
To be sure, “the days are evil,” but the Ephesians also have opportunities. These come in two forms. One is the opportunity for their own spiritual growth, which Paul will be enlarging on in verse 19. Another is the opportunity to witness to their many heathen neighbors, who still need to hear the good news of a Savior. Paul urges the Ephesians to pursue both avenues zealously.