Muspille, Heliand, and Christianity
Theories have been proposed about the relation between Ragnarök and the 9th century Old High German epic poem Muspilli about the Christian Last Judgment, where the word Muspille appears, and the 9th century Old Saxon epic poem Heliand about the life of Christ, where various other forms of the word appear. In both sources, the word is used to signify the end of the world through fire.[52] Old Norse forms of the term also appear throughout accounts of Ragnarök, where the world is also consumed in flames, and, though various theories exist about the meaning and origins of the term, its etymology has not been solved.[52]
Proto-Indo-European basis
Parallels have been pointed out between the Ragnarök of Norse religion and the beliefs of other related Indo-European peoples. Subsequently, theories have been put forth that Ragnarök represents a later evolution of a Proto-Indo-European belief along with other cultures descending from the Proto-Indo-Europeans. These parallels include comparisons of a cosmic winter motif between the Norse Fimbulwinter, the Iranian Bundahishn and Yima.[53] Víðarr's stride has been compared to the Vedic god Vishnu in that both have a "cosmic stride" with a special shoe used to tear apart a beastly wolf.[53] Larger patterns have also been drawn between "final battle" events in Indo-European cultures, including the occurrence of a blind or semi-blind figure in "final battle" themes, and figures appearing suddenly with surprising skills.