Have you ever read a letter in a room that is void of light? It is impossible?
A few years ago I spoke at a church in Capetown, South Africa. At the end of my talk, when I got off the stage, one of the leaders came up to me and said, "Ray, we have a new name for you." Of course, I was curious, so I asked him to share with me the name. He said, "Your Name to us, is "Letter."
He saw the astonishing look on my face, then said, "That's right, Letter, you didn't preach to us as most Westerners do, instead, you came as a letter, which was written on the hearts of us all."
II Corinthians 3
2 You yourselves are our letter, written on our hearts, known and read by everyone.
So the issue is not whether or not we are a letter, but rather, whether or not we are walking in the light so that others may read our letter (written in their heart).