The discussion about the figure of Judas has flared up anew since recently a Gospel of Judas was found. Repeatedly attempts have been made in the most varied ways to understand the nature and deed of Judas Iscariot. The interpretations range from Judas as traitor who had succumbed to evil to Judas as hero and initiate who even surpassed Jesus in readiness to sacrifice. His character and his deed raise the question of the nature and the meaning of evil in the world. The here somewhat expanded text of the lecture given in 2006 at the Frankfurt Book Fair is a contribution to answering this question and to a better understanding of Jesus' student Judas. For the Judas principle is active in all times in every pupil on the spiritual path and can only be overcome when we clearly see through it. To enable readers to form their own opinions, the passages in the canonical gospels pertaining to Judas are printed before the lecture. These along with the Gospel of Judas recently brought into public discussion being the texts with which the lecture deals.