Earlier in the book we learned that Harry’s parents died when he was only a baby, and he was raised by his Aunt Petunia and Uncle Vernon, who showed no interest in Harry at all. He was forced to live in a cupboard under the stairs, and was regularly punished for things that happened that were beyond Harry’s control.
While away at Wizarding School, Harry encounters this enchanted mirror. Harry soon discovers that this mirror shows you your greatest desire. So as Harry gazes into the mirror, he sees himself standing with his parents. They are smiling at him in loving approval. When Harry’s friend Ron gazes into the mirror, he sees himself winning the championship at a Wizarding sporting event.
When one of Harry’s professors finds out that Harry has found the mirror, he tells Harry, “…It shows us nothing more or less than the deepest, most desperate desire of our hearts… The happiest man on earth would be able to use the mirror of Erised like a normal mirror, that is, he would look into it and see himself exactly as he is… However, this mirror will give us neither knowledge or truth.” (Rowling, J.K. Harry Potter and the Sorcerer’s Stone. New York: Scholastic, Inc. 1997) This mirror showed the characters what they wanted to see, not what actually existed.
Sometimes we trick ourselves into believing only what we want to believe, instead of believing the truth. It is no different that dwelling only on our faults, except to the other extreme. At one extreme, we tell ourselves that we have no faults, while at the other we tell ourselves that we have no redeeming qualities.
When we look into Scripture, we look into a mirror, a mirror that tells us the truth. Scripture, like a mirror, shows us what we are, both the good and the bad.