Ephesians 4:18

Testify in the Lord. The exhortations that are to follow will be given in the light of Christ as the head of the church and the source of power for right living. Paul is not expressing merely his personal opinion. He feels deeply that which he is about to teach them. For similar affirmations see Acts 20:26; Rom. 1:9; 2 Cor. 1:23; Gal. 5:3; Phil. 1:8; 1 Thess. 2:5.

Walk. See on Eph. 2:2, 10.

Other Gentiles. Literally, “the rest of the Gentiles.” However, textual evidence favors (cf. p. 10) the omission of “other.” Paul urges that believers should be different from the Gentiles. The Ephesians themselves were once Gentiles, but now they belong to the “Israel of God” (Gal. 6:16).

Vanity. Gr. mataiotes (see on Rom. 8:20). The idea is not of conceit but of frivolous and empty aims. Without Christ the Gentile wanders on aimlessly, hopelessly, and recklessly. In Rom. 1:21-32 Paul draws a picture of utter depravity when man gives himself up to “vain” (mataios) imaginations. This degeneration has taken place in the governing part of the man’s nature, the mind, so that the rational faculties have yielded to misdirected or undirected imaginings. This vanity was not merely worthless, it was degrading.