Good is a very versatile word with many uses in everyday English. It is used as a noun, adjective, and adverb and is the root of the word "goodness." The common idea in almost all of its uses is that it suggests a desirable quality, something commendable, reliable, welcome, enjoyable, beneficent, kind, noble, admirable, propitious, exemplary, and very much welcome. In the word "goodness," the inner qualities of virtue, excellence of character, morality, and attitude that we see in a person's behavior come to the fore.
The Hebrew and Greek uses are similar, but the Hebrew, like the English, has a broader application. The Greek word, agathosune, at first glance seems very similar to chrestotes ("kindness"). However, closer examination of its use in the Scriptures reveals a word indicating zealous activity in doing good. Kindness or gentleness (chrestotes) is more passive.
William Barclay's Daily Study Bible commentary on Galatians says of these two words:
It [agathosune] is the widest word for goodness; it is defined as "virtue equipped at every point." What is the difference? Agathosune might, and could, rebuke and discipline; chrestotes can only help. Trench says that Jesus showed agathosune when He cleansed the Temple and drove out those who were making it a bazaar; but He showed chrestotes when He was kind to the sinning woman who anointed His feet. The Christian needs that goodness which at the same time can be kind and strong. (p. 51)
Agathosune is therefore active—even aggressive—goodness. The English word "goodness" includes many pleasing qualities whereas the Greek word indicates one particular quality. It is more than an excellence of character; it is character energized, expressing itself in active good. Agathosune is goodness, but it does not spare sharpness and rebuke to produce good in others. Thus God can correct, sometimes very severely, and it is goodness in action. Thus parents can correct their child, and it is good because it helps produce a responsible adult.
John W. Ritenbaugh
The Fruit of the Spirit: Goodness