The Kuzari is the classic Medieval book by Rabbi Yehuda HaLevi that provides a rational defense of Judaism against the polemics of Christianity, Islam and secular Philosophy.

The book itself is important reading for any Jewish educator.

Here is a pocket-size guide to the Kuzari for modern readers.

The basic Kuzari argument is eloquently articulated using modern examples in these three links:

1. Modern Kuzari – Lecture Format
2. (Audio mp3 version of #1)
3. Modern Kuzari – Graphical Format