Just as the tail is what propels the fish through the water, the Fishtail Illustration explains how the Gospel propels the believer through the Christian life.

There are many Christian books that explain life and scripture through the lens of the Gospel. But none of them have the lens itself. The Fishtail Illustration is that lens.

In 2006, Dr. Timothy Keller (the author's former pastor) challenged the world to come up with a new Gospel illustration. The Tail of the Fish