The nature of the ‘Colossian heresy’ remains obscure. It has gnostic features, but ChristianGnosticism is usually dated to the second century. It has elements of Judaism, but we know nothingof first-century Jewish gnosis. It may be a syncretistic ‘philosophy’, but such a description is barren, and explains nothing. It may be a kind of mysticism, but again the idea is difficult todefine, and the picture is left vague. I am proposing in this article to draw a comparison with anearly Gnostic document, the Apocryphon Johannis, which has clear Jewish roots; and to explain Colossians as Paul's response to a Jewish-Christian countermission which preached a myth close to, but distinct from, that in Apoc. Joh.