…and all our righteousnesses are as filthy rags —Isaiah 64:6
What did Isaiah mean when he wrote this passage? We must, of course, use the Bible as our text and as our guide to understanding the passage. We will first examine the Hebrew words underlying this passage.
What are righteousnesses? The plural form of this word used here, righteousnesses, is archaic. It is the plural of righteousness. According to Merriam Webster's Unabridged Dictionary, one definition of righteousness is a "righteous act, deed, or quality" and "righteous conduct". This definition is obsolete and is not used in modern syntax. Nevertheless, the word was not obsolete in 1611, when the King James Version was printed. Nor was it obsolete when the spelling and wording of the KJV were revised for printing in America in 1769. In both instances, the word meant righteous acts. One may look in 1611 King James Bible and find that the word there was "righteousnesses" just as it is in the KJV Bibles we have today. There is was no change to that word in 1769. Here is Isaiah 64:6 from the KJV 1611 version, "But we are al as an vncleane thing, and all our righteousnesses are as filthy ragges, and we all doe fade as a leafe, and our iniquities like the wind haue taken vs away." As one can see, the 1769 revision, which is the KJV we have today, did not change the word 'righteousnesses'.
It is obvious, especially in light of the original language, that the translators of the KJV had the obsolete definition, "righteous act, deed, quality, or conduct" in mind when they used the word "righteousnesses". To paraphrase, Isaiah said, "…all our righteous acts, or works, are as filthy rags".
Let us back that up with the Hebrew. The word rendered righteousnesses is צדקתינו, (tsedaqotinu-(pronunciation based upon diacritics not shown here). It is the noun common feminine plural construct suffix first person common plural form of צדקה (tsedaqah). The word is prefixed by כל (kol), meaning "all". In this morphology it means the righteousnesses of rulers, institutions, governments, men, and of God. The only way men can see righteousness in us is through our deeds, deportment, speech, lifestyle, etc., in other words, through our actions. Our actions are necessarily works. Consequently, righteous thoughts are not observable unless manifested in deeds. Therefore, we are speaking primarily of works that are outwardly observed. Of course, since God knows the thoughts of men as well as their deeds, they are important too. In this treatise, however, we are concerned with outward acts.
We have now established that righteousnesses are righteous acts. We know from the text that those righteous acts are as filthy rags in God's eyes.