“Wash me thoroughly from my iniquity–and cleanse me from my sin!” 
Psalm 51:2

Sin is spiritual filthiness.

Sin . . .
defiles the conscience,
corrupts the imagination,
depraves the heart,
perverts the will,
pollutes the mind,
sets the tongue on fire by hell,
stains the life, and
renders the man totally and eternally unfit for Heaven!

It is God’s work to cleanse a sinner. No one else can. The sinner cannot cleanse himself–he is without the means, the will, or the power! But God in mercy does, and He does it . . .
by His Son, atoning;
by His Spirit, renewing;
by His Providence, working;
and by His Truth, purifying.

The passage contains the believer’s prayer:
Wash me.”
“Wash me thoroughly.” 
It is from “my iniquity–my sin.”

Wash me, for . . .
I have discovered my filthiness;
I loathe myself on account of it;
and I long to be delivered from it!

Wash me thoroughly:
take out every stain,
erase every impression,
make me whiter than snow!

Sin always pollutes and defiles. A believer cannot rest in pollution, and therefore prays, “Wash me thoroughly from my iniquity–and cleanse me from my sin!”

~James Smith, “Daily Bible Readings for the Lord’s Household”

HT: Grace Gems