These days, the C.S. Lewis legacy is tied to the fantasy world of Narnia, with the Christian allegory well buried except for some cranky critics. The author, however, remains an intriguing figure in British letters. A conventional Anglican as a child, an atheist as a young man and finally, with nudges from Tolkien and C.K. Chesterton, a reconvert to Christianity. In this play by Mark St. German's, set just before World War II, the supreme scientist of the mind tussles with Lewis about faith, transcendence and the soul. The Off Broadway hit is the latest production by San Jose Repertory Theatre and stars Benjamin Evett and J. Michael Flynn.