Ephesians 5:8 says that converted persons are "light in the Lord" and should "walk as children of light." This light is revealed in all goodness, righteousness, and truth, mentioned in verse 9. This is what others should witness in us and be guided by as an example. Each of these three terms covers a different aspect of our witness.
Righteousness conveys legality. Psalm 119:172 defines righteousness as keeping the commandments of God, thus righteousness implies conformity to law. It is a narrower term than either truth or goodness. It indicates uprightness and a manifestation of justice. It can literally mean being right. God uses the illustration of a plumb line in Amos to portray what He means by righteousness. The person who is righteous has been measured against the standard of God's law and found to be in alignment. Therefore, righteousness should be a characteristic of a Christian. He is fair and just in his dealings with others, plays life by the rules and respects others' rights and possessions.
Earlier, in Ephesians 5:6, Paul speaks of deceit, things done in secret, and the hidden things of darkness. "All truth" is their opposite. The character of the life of the Christian is without deceit. Nothing is hidden, underhanded, or dishonest; nothing smacks of hypocrisy or pretense. The life of those walking in the light will be open, aboveboard, and transparent; it has nothing to conceal and never pretends to be something it is not.
New Testament goodness, agathosune, is a versatile and strong word that can be used either of the act or the intention motivating the act. It can be gentle or sharp, but the intention of the good person is always the well-being of the recipients of his goodness. An English word that covers some aspects of the Greek word is "benevolence." This "inclination to do good" seems to be Paul's intent in Ephesians 5:9.
Martyn Lloyd-Jones, in his Darkness and Light, a commentary on Ephesians 4 and 5, writes that this goodness is "indicative of a perfect balance in the various parts of the personality. A good man is a balanced man, a man in whom everything that is noble and excellent works harmoniously together" (p. 402). Thus he can be gentle or sharp, but what he does always has the right balance and is good.
Such a person tries to promote the happiness of all around him. He is not selfish or self-centered, but because he has this balance himself, he desires that others have it too. This is how God is. God looks upon us in our misery, the result of sin, and in His goodness leads us to repentance. Sometimes the path to repentance for us is sharp and painful, but it is always good.
On the more gentle side, God "makes His sun rise on the evil and on the good, and sends rain on the just and on the unjust" (Matthew 5:45). Although men are evil, He does this kindness out of His goodness.
In the converted person we see a pale reflection of this goodness. The good man is one who thinks about love, beauty, and truth—not just in the realm of majestic mountains, surging seas, gorgeous flowers, and sunsets, but more specifically in his fellow man. He wants to alleviate suffering and to mitigate wrongs. He consciously looks for ways to benefit others. Because he is not out to gratify himself, His works are the opposite of the self-centered works of darkness. The good person is the benefactor of the weak, helpless, and those in trouble—and sometimes even of the evil.
In the presence of Cornelius and his family, Peter says of Jesus, "God anointed Jesus of Nazareth with the Holy Spirit and with power, who went about doing good and healing all who were oppressed by the devil, for God was with Him" (Acts 10:38). The Scriptures speak frequently of Jesus' healing all who came to Him without qualification as to who they were. He sharply rebuked those who had the power to do good but did not. Though He at times ate with the "respectable" of the cities and villages, He was known to keep company with publicans and sinners. He flatly states that He did not come for those who were well, but for those who needed a physician (Matthew 9:12-13). As a man Jesus continued to follow the same pattern He established as God above, and in so doing He gave us a perfect example to follow within our contacts and power.