Complex sentence: Despite having been repeatedly discredited since its first appearance, the "prophecy" has proved a remarkably durable canard, returning most recently as a popular internet hoax promulgated on Usenet groups and antisemitic websites, where it is presented as authentic.
Split into simpler sentences: Despite having been repeatedly discredited since its first appearance, the "prophecy" has proved a remarkably durable canard. It has appeared most recently as a popular internet hoax promulgated on Usenet groups and antisemitic websites, where it is presented as authentic.