For ye were sometimes darkness, but now are ye light in the Lord: walk as children of light: For ye were sometimes (ποτε, formerly) darkness - While ye lived in darkness, ye lived in these crimes.
But now are ye light in the Lord - When ye were in heathenish darkness ye served divers lusts and pleasures, but now ye have the light - the wisdom and teaching which come from God; therefore walk as children of the light - let the world see that ye are not slaves to the flesh, but free, willing, rational servants of the Most High; not brutish followers of devil gods.