He restores my soul. He leads me in paths of righteousness for his name's sake. -- Psalm 23:3
Inward purification is a lifelong process. To remain in communion with God calls for a constant state of turning toward God and away from what we might call the "sense life". The word for that is metanoia. In Psalm 51, the repentant David cries out, "Create in me a clean heart, O Lord, and renew a right spirit with me."
Restoration begins with breaking down, planting begins with uprooting, life begins with death. I don't have cable or satellite, but, at a friend's house, our favorite shows to watch are things like "Fast and Loud" where they take some old car and hotrod it. You'll never have a beautiful, fast, reliable car until you take the body off, find the flaws, the broken, worn out parts, the rust, and corrosion. You can't just slap a new paint job on.
This is the (particularly, the evangelical) church's error in the modern age. We want to meet Jesus, have a nice visit, get a word, a blessing or an experience we can talk about then leave. We want to get cleaned up and looking good on the outside. We somehow think this exterior renewal will penetrate to the heart.
Far better that we continue looking externally rough while undergoing a metamorphosis from the inside out through a renewing of the mind (Romans 12:2). Who cares that we continue to look like a caterpillar for a while. The end result is what we seek.
The second part of our verse reminds us that not only does transformation take time, but that no restoration is permanent this side of the grave. We have to continue to walk with the Shepherd in His paths of righteousness in order to sustain and maintain the renewal and restoration. Lamentations 3:22-23 tells us that the Lord's steadfast love and mercies are unending and "new every morning". We can meet those new mercies and that ceaseless love with our own commitment to walk right today. No matter how good (or bad) yesterday was, today has the potential to be better, with more love and grace on God's part and a greater dedication to metanoia and purity on our part.