Jamieson, Fausset and Brown on Ephesians 4:24

24. put on the new man--Opposed to "the old man," which is to be "put off" (Ep 4:22). The Greek here (kainon) is different from that for "re-new-ed" (Ep 4:23). Put on not merely a renovated nature, but a new, that is, altogether different nature, a changed nature (compare Note,, see on Col 3:10).

after God, &c.--Translate, "Which hath been created (once for all: so the Greek aorist means: in Christ, Ep 2:10; so that in each believer it has not to be created again, but to be put on) after (the image of) God" (Ge 1:27; Col 3:10; 1Pe 1:15), &c. God's image in which the first Adam was originally created, is restored, to us far more gloriously in the second Adam, the image of the invisible God (2Co 4:4; Col 1:15; He 1:3).

in righteousness--"IN" it as the element of the renewed man.

true holiness--rather, as the Greek, "holiness of the truth"; holiness flowing from sincere following of "the truth of God" (Ro 1:25; 3:7; 15:8): opposed to "the lusts of deceit" (Greek, Ep 4:22); compare also Ep 4:21, "truth is in Jesus." "Righteousness" is in relation to our fellow men, the second table of the law; "Holiness," in relation to God, the first table; the religious observance of offices of piety (compare Lu 1:75). In the parallel (Col 3:10) it is, "renewed in knowledge after the image," &c. As at Colosse the danger was from false pretenders to knowledge, the true "knowledge" which flows from renewal of the heart is dwelt on; so at Ephesus, the danger being from the corrupt morals prevalent around, the renewal in "holiness," contrasted with the Gentile "uncleanness" (Ep 4:19), and "righteousness," in contrast to "greediness," is made prominent.