William Burkitt on Ephesians 5:8

Here the Ephesians are put in mind of the darkness and blindness of their heathen state, before the light of the gospel came among them; they were not only dark, very much in the dark, but darkness itself: he next acquaints them with their happy condition, by entertaining of the gospel of Christ; they therefore became light in the Lord, they were savingly enlightened by the word and Spirit of God; and accordingly he urges them to walk answerably to their Christian profession, Walk as children of the light.

Note here, 1. That the state which every soul is in by nature, and before conversion, is a state of spiritual darkness; like men in the dark, they go they know not whither, they do they know not what, they stumble and fall they know not how and when.

Note, 2. That all those whom God calls effectually out of the darkness and ignorance of their natural and unregenerate state, he doth enlighten them by his word and Holy Spirit.

Note, 3. That such as are so called and enlightened, ought to walk suitably to their privilege, and answerably to their high and honourable profession. Walk as children of light; that is, holy, humbly, cheerfully, thankfully, before God; exemplarily and unblamably before the world.