If you are one who knows this saying to be taken from scripture, you might be immediately defensive at the idea of me criticizing it... But let me ask you a question the people who use this phrase in sermon after sermon never ask: Is it really "scriptural" to repeat "Your works are filthy rags" in the way we do? Are you certain? Just because the phrase is in the Bible - does that mean we're using it properly or for the same reason? Is it even a correct perspective to take in holding it over the heads of others?
You may have already guessed (you're fairly clever, after all) that I don't think the answer to any of the above questions should be "yes."