Plass wrote some years ago about The Devil's Graffiti, drawing on Jeremiah 31 where God declares that he will write His laws on our hearts. A little bit of theological work is probably needed here to understand what this means. Certainly I think it a mistake to see it legalistically. Good laws increase freedom and I believe what Jeremiah 31 is saying is that God would change cold hearts such that external laws become less and less important. Plass's observation was that sometimes before God can begin to write said laws he first has to scrub away to remove the Devil's Graffiti that's in the way.
I have written elsewhere, in a different context about the poisonousness of lies. I don't think you have to believe in the spiritual interpretation to see the truth of the observation. Most people carry with them deep scars and things that have been burned into them that aren't true. This is of course, most profound in people who suffered in childhood - particularly from abuse but it is also true that some of us accumulate it over the years through constant knock-backs or repeated messages from the world around us. These lies - for that is what they are - are often deeply poisonous, affecting relationships, confidence and hope.
The problem, assuming your heart is anything like mine, is that negative graffiti has built up over the years leaving very little space for anything else. The devil gets busy with his infernal aerosol can! Things people have said, failures that have destroyed confidence, traumatic experiences, profound, unforgettable embarrassments – all sorts of things.Usually each one tells you a lie about yourself:you will never succeed,you are not lovable,God has cast you aside because of that sin,you’re boring,happiness is impossible,your life has no purpose.The almost invariable untruthfulness of these scrawling should be sufficient indication of their ultimate authorship. The father of lies is anxious that our hearts be covered with a confused mass of misinformation, some of it etched so deeply it comes close to breaking our hearts.
My own personal graffiti - well there's probably a few bits - but the most important one said simply this; "You are unlovable." I can chart particular experiences that are probably the origin of these words but it doesn't really matter. These words, scarred into me, often made liars of good people - for it didn't matter how much people expressed their love, it just wasn't actually possible for people to love me. It's not that I doubted them, I doubted me.
I believe in a God of healing. These words are faded now - God has spent a long time scrubbing away to remove them. In fact they're not visible most of the time; it's only when the rain falls in a certain way that you can see them at all.
I have seen in the lives of many people the poison of such lies. I think recognising them for what they are is the first step to ridding ourselves of them, the first part of the healing the process.