For many years, I heard the "brethren" say, "God is done with man in the flesh." I think I'm starting to see just a little bit of what they meant.
It seems when we try to approach God as "man in the flesh," we fall into one of two opposite errors. Either we are so aware of our own unworthiness to come into God's presence that we come in hesitatingly, groveling and bemoaning our worthlessness (like many or most traditional Protestant churches); or we come in self-confident and swaggering, sure that we're good enough to be there (like more modern "seeker-friendly" groups). Those who fall in the first group seem to be constantly looking for improvement in themselves, those in the second are characterized by an irreverent familiarity with God.
It's so very hard to learn the lesson that God has no intention of improving the flesh. God's purpose in Christ is to bring sinners to Himself: but it's not to leave them sinners. We are stuck in sinful bodies, it is true; but we are new creations trapped in an old creation's body. Eventually the body will be changed into incorruptibility, but that's still future. But until we get there, we carry around this thing called "the flesh."
The change from being an old creation to being a new one is significant, because it means we're starting something very new. God isn't looking to improve sinners, He's starting in a new place. It's true we all sin, it's true we all fall short of the glory of God, it's true we all carry the flesh around with us. But it's just as true that God's not looking on His children as sinners and setting out to make them better. And so we ought not to consider ourselves in that light either.
We who approach God are "purged worshippers," who, "once cleansed, have no more conscience of sins." We are to go confidently (not self-confidently!) into God's presence, because we are confident in our Great High Priest, who invites us in. We don't hang around the door nervously, waiting for God to make us worthy before we approach. I get the impression that a lot of pious Christians are hesitant to go in: maybe next Sunday they'll be worthy, but this Sunday they'd better hang back a bit. This behaviour is nothing else than trying to get to God on my own, rather than on the basis of His Son's blood: it's exactly the same thing as trying to swagger into God's presence, sure He couldn't possibly turn me back. While I'm sure the one who hesitates has a more Scriptural concept of God's holiness and man's worthlessness than the lout who presumes on his own worth; neither one of them is trying to approach God in the only way we have: the blood of Christ.
God is gracious, and will tolerate a lot from His children. I don't want to in any way cast aspersion on God's goodness. On the other hand, we need to take God at His word.