I think that many of us, when Christ has enabled us to overcome one or two sins that were an obvious nuisance, are inclined to feel (though we do not put it into words) that we are now good enough. He has done all we wanted Him to do, and we should be obliged if He would leave us alone.
But the question is not what we intended ourselves to be, but what God intended us to be when He made us.
Imagine yourself as a living house. God comes to rebuild that house. At first, perhaps, you can understand what God is doing. He is getting the drain right and stopping the leaks in the roof and so on. You knew that those jobs needed doing and so you are not surprised.
But presently God starts knocking the house about in a way that hurts abominably and does not seem to make sense. What on earth is God up to? The explanation is that God is building quite a different house from the one you thought of––throwing out a new wing here, putting on an extra floor there, running up towers, making courtyards.
You thought you were going to be made into a decent little cottage, but God is building a palace. He intends to come and live in it Himself.
––– C. S. Lewis,
Mere Christianity
