Charles Ellicott Commentary Isaiah 64:6

"For we are all become as one that is unclean, and all our righteousnesses are as a polluted garment: and we all do fade as a leaf; and our iniquities, like the wind, take us away." — Isaiah 64:6 (ASV)

We are all as an unclean thing ... —Better, as "he who is unclean," namely, like the leper of Leviticus 13:45.

Filthy rags point to that which, to the Israelite, was the other most extreme form of ceremonial uncleanness, as in Ezekiel 36:17.

Have taken us away — namely, far away from the light and favor of Jehovah.