Ephesians 4:23

Conversation. Gr. anastrophe, “manner of life,” “conduct,” “behavior.” For comment on the related verb anastrepho see on ch. 2:3. The former manner of life has been described in ch. 4:17-19. The former sinful nature is to be stripped off once and for all, never to be put on again; the new nature is to be put on (see on v. 24). The robe of righteousness is to replace the filthy garments of self-righteousness.

The old man. See on Rom. 6:6; cf. Col. 3:9. This expression seems to mean more than simply the old acts or habits and to include the very mind and nature that are the source of every act. The old man had died (Rom. 6:6) and should not be revived.

Is corrupt. Literally, “being corrupted,” or “corrupting itself.” The form of the word indicates continuance or progression in corruption in the condition of “the old man.” Sin is a disintegrating factor in the life, a cancerous growth in the spiritual body.

Deceitful lusts. Literally, “lusts of the deception.” The phrase stands in contrast with “truth” (v. 21). If men sensed the bondage and corruption that sin brings to them, it would appear as it really is, a frightful thing. However, its real character is concealed until it has enslaved its victims. The lusts of the flesh are deceitful because they promise happiness but give sorrow, promise freedom but give slavery, promise immunity from the results of wrongdoing, only to bring destruction.