and all our righteous deeds are like a polluted garment.
We all fade like a leaf, and our iniquities, like the wind, take us away."
- Isaiah 64:6
Using clothing as a metaphor for sin is a recurring theme in Scripture. Here, Isaiah compares the best actions of fallen men to filthy garments. The theme continues in Zechariah 3:3-5.
"Now Joshua [the high priest, v.1] was standing before the angel, clothed with filthy garments. And the angel said to those who were standing before him, 'Remove the filthy garments from him.' And to him he said, 'Behold, I have taken your iniquity away from you, and I will clothe you with pure vestments.' And I said, 'Let them put a clean turban on his head.' So they put a clean turban on his head and clothed him with garments. And the angel of the Lord was standing by." Confer also Exodus 28:36-38. The Angel of the Lord represents the presence of the pre-incarnate Second Person of the Trinity, the Christ of the New Testament.
The point here is that the filthy garments of sin represent the natural condition of fallen man. In contrast, the clean garments are placed upon him by the external application of Christ. This is the difference between grace and works-righteousness.
In the New Testament, the Apostle picks up the changing-of-garments theme, commanding us to "put on Christ," in Romans 13:14 and Galatians 3:27. What does this gain us? Philippians 3:9, "[that I may] be found in Him, not having a righteousness of my own that comes from the law, but that which comes through faith in Christ, the righteousness from God that depends on faith." As English Presbyterian Walter Marshall said in his book, The Gospel Mystery of Sanctification, "The end of Christ's incarnation, death, and resurrection, was to prepare and form a holy nature and frame for us in Himself, to be communicated to us by union and fellowship with Him; and not to enable us to produce in ourselves the first original of such a holy nature by our own endeavours."
So, what do you want to wear when you stand before God in eternity: the polluted garments that you have from Adam? Or the clean garments of Christ's righteousness, received by faith?