"Who can say, 'I have made my heart clean, I am pure from my sin'?"
All fallen people actually *do* say this (statement above), in their heart of hearts. The problem is: it is not true. First of all, we *cannot* "make [our hearts] clean"; and, because of this, on our own, we are *never* "pure from [our] sin." What the NT calls the "flesh" is the agency that seeks to convince us that we really *are* clean before God--when, in fact, we are not.
Only an "alien" righteousness can really and fully purify us. This righteousness is from Another--and not from within ourselves. This cleansing, this justification comes from Christ, and is imputed to believing churchmen by faith. Is your heart clean? Are you pure from your sin? You are, if you trust Jesus (alone) to do it.
[Puritan quote of the day: "No one grows so much as those who have their growth stopped for a time." --Richard Sibbes, in "Glorious Freedom"]
