In an oracle typical of the eighth-century prophets (see Introductory Issues), Isaiah calls Israel to care for the oppressed and those in need of particular care, particularly the orphan and the widow.
The Torah frequently links orphans, widows, and aliens in its call for justice (for example, Exodus 22:21-22; Deuteronomy 24:17), because these groups were without power, cut off from the normal safety networks of land and family. They were particularly vulnerable, and biblical law therefore required that they not be taken advantage of--more, in fact, that they be given special attention.
Having failed to reach out to those for whom God cares, Israel's hands are "full of blood" (Isaiah 1:15), but God has not given up on them. Despite the terrible word of judgment Isaiah must deliver to his whole generation (6:9-13), the possibility of repentance and renewal remains open for those who "are willing and obedient." They might still wash themselves and become clean.
As part of an ongoing lawsuit that seeks to make hearers see their faults and turn to God, the verbs of vv. 18-19 should be read conditionally rather than as declarative promises: not that your sins "shall be" like snow, etc. (NRSV and most translations), but that they "may become" white as snow (NAB; see also NJPS). The matter is still open. God offers renewed purity, but refusal will mean destruction (see Deuteronomy 30:19).
16 Wash yourselves; make yourselves clean;
remove the evil of your doings
from before my eyes;
cease to do evil,
17 learn to do good;
rescue the oppressed,
defend the orphan,
plead for the widow.
18 Come now, let us argue it out,
says the Lord:
though your sins are like scarlet,
they shall be like snow;
though they are red like crimson,
they shall become like wool.
19 If you are willing and obedient,
you shall eat the good of the land;
20 but if you refuse and rebel,
you shall be devoured by the sword;
for the mouth of the Lord has spoken.
New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org