Everyone who has this hope set on him purifies himself, even as he is pure.
"Purifieth" is hagnizei, in the present active indicative, and connotes continuous action. A child of God who is motivated by this hope keeps on purifying himself and thus keeps his hope both "sure and stedfast" (Hebrews 6:19). While it is the precious blood of Christ that constantly cleanses the Christian of all sin (1 John 1:7), the Christian has a duty before God to purify himself on a continuing basis. We purify ourselves by abstaining from every form of evil, by living clean and chaste lives, and by keeping ourselves unspotted from the world. This code of conduct does not mean that we can live above sin. Chapter one, verses 8-10, has impressed upon us that there is no one who can claim total freedom from sin. "The spirit indeed is willing, but the flesh is weak." (Matthew 26:41)