Ephesians 4: 17-24 The New Life
(17) Now this I say and testify in the Lord, that you must no longer walk as Gentiles do, in the futility of their minds. (18) They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart. (19) They have become callous and have given themselves up to sensuality, greedy to practice every kind of impurity. (20) But that is not the way you learned Christ!--(21) assuming that you have heard about him and were taught in him, as the truth is in Jesus, (22) to put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, (23) and to be renewed in the spirit of your minds, (24) and to put on the new self, created after the likeness of God in true righteousness and holiness.
John 16: 1-15 Work of the Holy Spirit
(1) I have said all these things to you to keep your from falling away. (2) They will put you out of the synagogues, indeed, the hour is coming when whoever kills you will think he is offering service to God. (3) And they will do these things because they have not known the Father, nor me. (4) But I have said these things to you, that when their hour comes you may remember that I told them to you. "I did not say these things to you from the beginning, because I was with you. (5) But now I am going to him who sent me, and none of you asks me. "Where are you going?" (6) But because I have said these things to you, sorrow has filled your heart. (7) Nevertheless, I tell you the truth: It is to your advantage that I go away from you, for if i do not go away, the Helper will not come to you. (8) And when he comes; he will convict the world concerning sin and righteousness and judgment: (9) concerning sin, because they do not believe in me; (10)concerning righteousness, because I go to the father and you will see me no longer. (11) concerning judgement because the ruler of this world is judged. (12) "I still have many things to say to you , but you cannot bear them now. (13) When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come. (14) He will glorify me, for he will take what is mine and declare it to you. (15) All that the Father has is mine; therefore I said that he will take what is mine and declare it to you.
"And to be renewed in the spirit of your minds" Ephesians 4: 23 is an exhortation to the readers of this letter to not fall back into the patterns of thinking and the resultant behavior which was part and parcel of the Gentile world around the new believers.
However, is this verse from Ephesians simply about the past as far as we are concerned? One thing is for sure, the world around us in 2020 is everything the Gentile world was when this letter was written in the late 50's AD or early 60's AD, so I would surmise its as relevant to Christians today as it was to new believers in the Jesus movement in early Christianity.
Paul often used the notion of a "renewed" mind. He talks about it in his letter to the church in Rome in 12: 2-3 and we see it here in Ephesians 4:23 as well as verses like Philippians 4: 6-8--"Whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is lovely, whatever is commendable, if there is any excellence, if there is any anything worthy of praise, think about these things".
A renewal of mind is training the mind to focus on the goodness and holiness of God and to follow through in the life choices of that good and holiness in a world filled with distractions and temptations to live as the world, or live to your own carnal desires. The Spirit is operative in this work, but the Spirit can't force you to have you mind set and renewed. It takes day in and day out training and renewal of the mind.