Live in the light. Do not grieve the Holy Spirit of God,

Ephesians 4:17-32
Insist on it in the Lord, that you must no longer live as the Gentiles do, in the futility of their thinking. Having lost all sensitivity, they have given themselves over to sensuality so as to indulge in every kind of impurity, with lust for more.

Your did not come to know Christ that way. Surely you heard of him and were taught in him in accordance with the truth that is in Jesus. Put off  your old self which is being corrupted by its deceitful desires; to be made new in the attitude of your minds; and to put on the new self, created to be like God in true righteousness and holiness.

Put off false hood and speak truthfully to his neighbor. "In your anger do not sin." Do not let the sun go down while you are still angry, and do not give the devil a foothold. Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen. And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption.
Why?
Live in the light!
Salvation is God's free gift, but it carries with it the obligation to live and behave from that point on as God wants.
This means deliberately discarding the old, selfish way of life, shedding former habits and letting the new life change our thinking and remold our pattern of behavior.
Paul does not stop at generalities: he is quite specific in his 'does' and 'don'ts' . The new life calls for truth and honesty; no harboured grudges結怨, no spite 惡意and bitterness - instead kindness and a new readiness to forgive.
In a word, we are to copy God's own character, lives of sacrificial love which will bear the searching light of God. Once we belonged to the dark: now we are children of light.
Why?
Live in the light, to be children of light in God. I have to active to do the right thing that response the calling from the Lord.