Introduction to “Gnosticism”: Ancient Voices, Christian Worlds by Nicola Denzey Lewis, from Oxford University Press, may be of interest. There’s an interesting review of the work over at Peje Iesous at “Nicola Denzey Lewis’ Textbook On the Gnostic Literature Is Really Useful (Or: Why I’m Glad My Class Failed Before It Got Off the Ground)” [HT Jared Calaway] which may also interest you, especially since it highlights this book’s apparently good exploration of the way the term “Gnosticism” can be problematic. The review seems to suggest this is a new work for 2013, but I notice that Amazon has 2012 as the publication date; but, it is at least recent for some reasonably flexible value of recent either way.

“Discovered in Egypt in 1945, the fascinating and challenging Nag Hammadi writings forever changed our understanding of early Christianity. State-of-the-art and the only volume of its kind, Introduction to “Gnosticism”: Ancient Voices, Christian Worlds guides students through the most significant of the Nag Hammadi texts. Employing an exceptionally lucid and accessible writing style, Nicola Denzey Lewis groups the texts by theme and genre, places them in the broader context of the ancient world, and reveals their most inscrutable mysteries.

Ideal for use in courses in Early Christianity/Origins of Christianity, Christianity to 1500, Gnostic Gospels, Gnosticism, Early Christian Writings, Orthodoxy and Heresy, and New Testament Studies, Introduction to ‘Gnosticism’ is enhanced by numerous pedagogical features, including images of the manuscripts, study and discussion questions, annotated bibliographies, tables, diagrams, and a glossary.” [via]