As a young boy, theologian Alister McGrath enjoyed experimenting with chemicals in his school's laboratory. He liked to drop a tarnished coin into a beaker of diluted nitric acid. He often used an old British penny bearing the image of Queen Victoria. Because of the accumulated grime, Her Majesty's image couldn't be seen clearly. But the acid cleansed away the grime and the Queen's image reappeared in shining glory.
We know, to be sure, that we were created in the image of God (Genesis 1:26), but that image has been defaced by our sin. We are still His image-bearers, however.
Once we invite Jesus to enter our lives as Savior, He goes to work to restore the original image. He transforms us to make us like Himself. This process is described as putting off some behaviors and putting on others. For example, we are to "put off all these: anger, wrath, malice, blasphemy, filthy language" and to "put on love".
Unless, and until, our sin-tarnished souls are cleansed by Jesus' forgiveness, God's image is obscured in our lives. But when we trust Jesus' sacrifice on the cross, we are forgiven and the restoration begins (Vernon C Grounds).