Alas for you, lawyers and Pharisees, hypocrites! You clean the outside of cup and dish, which you have filled inside by robbery and self-indulgence! Blind Pharisee! Clean the inside of the cup first; then the outside will be clean also. Matt. 23:25, 26, N.E.B.
I once bought a large hydraulic jack at a yard sale, and I was excited. For only $15 I brought home a shiny, hefty-looking piece of equipment that the pleasant lady behind the table had assured me was almost new. As I tried it out under our car, I bragged about my clever purchase to my wife. My face became red with anger (and embarrassment) as the jack oozed hydraulic fluid all over the floor and the car sank slowly down.
Jesus is absolutely committed to reality. He wants everything in His kingdom actually to be on the inside what it claims to be on the outside. Nothing short of this would allow us to trust each other throughout eternity. No wonder He spoke so severely to those religious leaders who were veterans of pretense. Claiming to speak on behalf of God, the Pharisees were giving the people reason to believe that God Himself would be content with an outward show of righteousness, overlooking the reality of the inner condition. But Jesus was telling all who would hear that His Father, too, was committed to reality.
This raises an interesting question. If Jesus decries the idea of a person being clean only by outward appearance while in reality being still attached to sin, then what is the difference between an outwardly scrubbed cup and the "robe of Christ's righteousness," as it has often been understood? Rather than hiding our real condition from the eyes of man (as taught by the clean cup metaphor), the robe of Christ's righteousness is presumed to hide our real condition from the eyes of God. This idea suggests we can "hide" under the substitutionary merit of Christ's perfect righteousness and the Father will accept us to be what in reality we are not.
But the robe of Christ's righteousness is never intended to be a falsification of reality. Christ does not provide it either to fool or to change the Father. The robe is Christ's potent statement of the Father's love and acceptance for the sinner, which--when claimed and worn with pride--will produce actual cleanness within the sinner. And God need make no provision to hide sins that He is confident He can heal.