Humanity is awash in whitewash and short-term humanist solutions that only touch the surface of our needs. What we really need is a permanent inner cleansing. He was showing the spiritual leaders of his day the depth of their need by comparing their lifeless faith to the state of a graveyard. The outside of their graves were clean and white but just below the surface, all sorts of festering decay was taking place. Their inner corruption was well hidden from human eyes but not from God.
Whitewash is watered down paint.
A little truth mixed in with a lot of water can make us look, and even feel, righteous for a while, but it does nothing to change our hearts. Jesus never trafficked in whitewash. He confronted the spiritual leaders of his day with the stark undeniable truth of the corruption of their own hearts and then offered them an elegant solution. Our dead hearts need a touch of life. We also like to remind you of the hope you have in Jesus and the endless love He has for you.