Book excerpt: Spiritual writer, theologian, and philosopher Jesuit Fr. Robert Spitzer tackles the topic of recognizing and overcoming spiritual evil. His focus is the human heart. His goal: our moral and spiritual transformation, which leads to true peace and genuine happiness. The book is divided into two main parts: the realities of God's goodness and of spiritual evil, and recognizing and overcoming diabolical tactics, which range from temptation and deception to the Deadly Sins. Father Spitzer shows readers how to experience God's peace even during times of suffering and persecution. He examines the basics of the spiritual life and Christian mysticism, including the contemplative dimension. He explains the purgative, illuminative, and unitive aspects of spirituality, as well as the Lord's consolation and the passive Dark Night of the Spirit. Father Spitzer provides the biblical and theological background of Jesus' victory over Satan. The author also explores the reality of the Devil, including extraordinary manifestations of diabolic activity such as possession. He recalls the true story of the famous possession case on which the novel and film The Exorcist were based. In the final sections of the book the author explains: how diabolical spiritual forces operate how temptation works, and what to do to defeat it the "deadly sins" and how to overcome them