You've probably already read the
Wikipedia article on Quetzalcaotl. If you haven't, it has
some decent information on the subject, such as how a feathered serpent could become associated/interchangeable with a historical figure. The section
most pertinent to this conversation comes under the section of the article titled "In Modern Times", which says:
Some theories associate Quetzalcoatl with Vishnu, the second God of the Hindu Trinity. Vishnu is said to have an Eagle (Garuda) and a Serpent
(Adisesha) as his vehicle. [1] Some modern esoteric groups, sometimes called "Mexicanistas", have mixed the cult of Quetzalcoatl with modern
esoteric practices. There are also claims that Quetzalcoatl was either a lone viking, a Phoenician, Levite, a survivor from Atlantis, or even an
extraterrestrial[citation needed].
Some followers of The Church of Jesus Christ of Latter-day Saints claim that the idea of Quetzalcoatl descended from the visitation of Jesus Christ to
the Americas after his resurrection in about 34 AD. This is recorded in great detail in The Book of Mormon following the end of his ministry in Judea.
This claim is based in the idea that the name (translated as Feathered Serpent) was given because Christ was born and preached among the poor
(serpents move along the ground) and because of the manner in which he appeared in Mesoamerica (descending from heaven). This idea is most prominently
voiced by the Foundation for Ancient Research and Mormon Studies (FARMS) and is not official doctrine of The Church of Jesus Christ of Latter-day
Saints.
In
The Secret Teachings Of All Ages Manly P. Hall demonstrates Quetzalcoatl as a solar god,
like Bacchus, Mythras, or Christ:
One of the most remarkable of the crucified World Saviors is the Central American god of the winds, or the Sun, Quetzalcoatl, concerning whose
activities great secrecy was maintained by the Indian priests of Mexico and Central America. This strange immortal, whose name means feathered snake,
appears to have come out of the sea, bringing with him a mysterious cross. On his garments were embellished clouds and red crosses. In his honor,
great serpents carved from stone were placed in different parts of Mexico.
The cross of Quetzalcoatl became a sacred symbol among the Mayas, and according to available records the Maya Indian angels had crosses of various
pigments painted on their foreheads. Similar crosses were placed over the eyes of those initiated into their Mysteries. When Cortez arrived in Mexico,
he brought with him the cross. Recognizing this, the natives believed that he was Quetzalcoatl returned, for the latter had promised to come back in
the infinite future and redeem his people.
In Anacalypsis, Godfrey Higgins throws some light on the cross and its symbolism in America: "The Incas had a cross of very fine marble, or beautiful
jasper, highly polished, of one piece, three-fourths of an ell in length, and three fingers in width and thickness. It was kept in a sacred chamber of
a palace, and held in great veneration. The Spaniards enriched this cross with gold and jewels, and placed it in the cathedral of Cuzco. Mexican
temples are in the form of a cross, and face the four cardinal points. Quexalcoatl is represented in the paintings of the Codex Borgianus nailed to
the cross. Sometimes even the two thieves are there crucified with him. In Vol. II. plate 75, the God is crucified in the Heavens, in a circle of
nineteen figures, the number of the Metonic cycle. A serpent is depriving him of the organs of generation. In the Codex Borgianus, (pp. 4, 72, 73,
75,) the Mexican God is represented crucified and nailed to the cross, and in another place hanging to it, with a cross in his hands. And in one
instance, where the figure is not merely outlined, the cross is red, the clothes are coloured, and the face and hands quite black. If this was the
Christianity of the German Nestorius, how came he to teach that the crucified Savior was black? The name of the God who was crucified was
Quexalcoatl.
Interesting to say the least. Now would Gandalf fit into this solar deity archetype? He did rise again after being swallowed by the earth.