A.T. Robertson Commentary Ephesians 4:23

"and that ye be renewed in the spirit of your mind," — Ephesians 4:23 (ASV)

That ye be renewed (ανανεουσθα). Present passive infinitive (epexegetical, like αποθεσθα, of αληθεια εν τω Ιησου) and to be compared with ανακαινουμενον in Col 3:10. It is an old verb, ανανεοω, to make new (young) again; though only here in N.T.

The spirit (τω πνευματ). Not the Holy Spirit, but the human spirit.