What does Isaiah 1:17 mean?

The Lord is telling the people of Judah how to change, how to restore their relationship with Him. He has described them as a sinful nation and covered in iniquity (Isaiah 1:4). He has called their sacrifices and offerings and religious gatherings meaningless (Isaiah 1:13) because of their sinful lifestyles.

Now the Lord tells them how to learn to do good. They must make themselves clean by stopping their evil practices. The form of good is revealed in this verse as the good the Lord always desires from any people in community: Bring about justice for those who are wronged, especially the orphans and widows, as well as intervene to stop the powerless from being oppressed by the powerful.

The natural course of any people group is for the rich to become richer and to take advantage of the poor and powerless for their own gain. Human nature is corrupt that way. Social goodness requires communities to act together to interrupt these cycles and hold the powerful accountable for wrongdoing while standing up for those without resources to stand up for themselves. God's chosen people Israel, above all people, should practice this goodness.

Isaiah has already compared the people of Judah to those in Sodom and Gomorrah (Isaiah 1:9–10). He wants them to get off the path that leads to similar destruction. Sodom's sexual immorality and violence were not their only sins. A culture can be depraved in many ways; all wickedness means rejection of God. Other Scriptures note that the cities destroyed in Genesis chapter 19 were guilty of many other crimes. Their refusal to do the kind of good mentioned here contributed to their destruction by the Lord: "Behold, this was the guilt of your sister Sodom: she and her daughters had pride, excess of food, and prosperous ease, but did not aid the poor and needy" (Ezekiel 16:49).