Wherefore be ye not unwise, but understanding what the will of the Lord is.
Wherefore - since ye need to walk circumspectly, choosing the right opportunity of good.
Unwise, х afrones (G878)] - different Greek from Ephesians 5:15; 'foolish,' 'senseless.'
Understanding - not merely knowing as a fact (Luke 12:47) but knowing with thoughtful understanding.
The will of the Lord - how each opportunity is to be used. The Lord's will ultimately is our "sanctification" (1 Thessalonians 4:3); and that "in every thing," meantime, we should "give thanks" (1 Thessalonians 5:18: cf. above, Ephesians 5:10).