Azriel, while fascinating historically, is a fairly shallow character, an avenging angel made flesh once again. His faith and the testing of that faith comprise his sole motivation. At each step, he tries to determine what God would want him to do, what more God requires of him, and what steps he must take to reach heaven. As a metaphor, however, Azriel is an excellent illustration of the childlike ideal of faith. He accepts instruction from his masters, and when they betray him, he waits for signs from Yahweh himself. Through his faith he is transformed, freed of the need for a master and from dependence on the Bones. He is sustained by water and his faith in God alone.

Far more complex is the character of Gregory Belkin. A Hasidic prodigy, he turns against his faith and heritage, choosing instead to found a cult to redirect people's...