All of the text below is quoted directly from Biblical Literarcy - the most important people, events, and ideas of the Hebrew Bible by Rabbi Joseph Telushkin. (Harper Collins, New York, 1997, pp 326-327.)
In an effort to convey to his fellow Israelites in simple, direct terms the sort of life God expects them to lead, Micah speaks of three essences:
He has told you, O man, what is good.
And what the Lord requires of you.
Only to do justice,
And to love goodness
And to walk modestly with your God (6:8).
The insistence on justice follows from the Torah's admonition, "Justice, justice you shall pursue" (Deuteronomy 16:20). Tzedek, the Hebrew for "justice," is the root of the word tzedaka, which is translated as "charity," but which literally is a derivative of "justice" (from the biblical perspective one who does not give tzedaka is not merely uncharitable, but unjust.)
Micah's injunction "to love goodness" recalls Deuteronomy 6:18, "Do what is right and good in the sight of the Lord," and Proverbs 2:20, "So follow the way of the good, and keep to the paths of the just."... (PamBG: I have omitted here some supporting arguments the author makes from the book of Jeremiah.)
Micah's final demand is "to walk modestly with your God." The sort of faith that leads one to believe that he or she knows exactly what God requires in every situation can make a person arrogant. This passage demands humility of believers.
The pursuit of justice, an obsession with doing good deeds, and humility, these are what constitute for Micah a godly person. As Rabbi Hillel (first century B.C.E.) remarks after offering a similar ethical statement of Judaism's essence: "All the rest is commentary" (Babylonian Talmud, Shabbat 31a).