Mexico (Aztec) the worship of Quetzalcoatl was ubiquitous. The most important center was Cholula where the world's largest pyramid was dedicated to his worship. In Aztec culture depictions of Quetzalcoatl were fully anthropomorphic. Quetzalcoatl was associated with the winded god Ehecatl and is often depicted with his insignia: a beak like mask.
Based on the Teotihuacan iconographical depictions of the feathered serpent, archaeologist Karl Taube has argued that the feathered serpent was a symbol of fertility and internal political structures contrasting with the War Serpent symbolizing the outwards military expansion of the Teotihuacan empire.
Historian Enrique Florescano also analysing Teotihuacan iconography shows that the Feathered Serpent was part of a triad of agricultural deities: the Goddess of the Cave symbolizing motherhood, reproduction and life, Tlaloc, god of rain, lightning and thunder and the feathered serpent, god of vegetational renewal. The feathered serpent was furthermore connected to the star venus because of this star's importance as a sign of the beginning of the rainy season. To both Teotihuacan and Mayan cultures Venus was in turn also symbolically connected with warfare.
While not usually feathered, classic Maya serpent iconography seems related to the belief in a sky, venus, creator, war and fertility related serpent deity. In the example from Yaxchilan the Vision Serpent has the human face of the young maize god, further suggesting a connection to fertility and vegetational renewal, the Mayan Young Maize god was also connected to Venus.
In Xochicalco depictions of the feathered Serpent is accompanied by the image of a seated, armed ruler and the hieroglyph for the day sign 9 Wind. The date 9 wind is known to be associated with fertility, venus and war among the Maya and frequently occurs in relation to Quetzalcoatl in other Mesoamerican cultures.
Based on the iconography of the feathered serpent deity at sites such as Teotihuacan, Xochicalco, Chichen Itza, Tula and Tenochtitlan combined with certain ethnohistorical sources, historian David Carrasco has argued that the preeminent function of the feathered serpent deity throughout Mesoamerican history was as the patron deity of the Urban center, a god of culture and civilization.
Quetzalcoatl as depicted in the Codex Borbonicus.
The worship of Quetzalcoatl sometimes included animal sacrifices, and in colonial traditions Quetzalcoatl was said to oppose human sacrifice.
Mesoamerican priests and kings would sometimes take the name of a deity they were associated with, so Quetzalcoatl and Kukulcan are also the names of historical persons.
One noted Post-Classic Toltec ruler was named Quetzalcoatl; he may be the same individual as the Kukulcan who invaded Yucatan at about the same time. The Mixtec also recorded a ruler named for the Feathered Serpent. In the 10th century a ruler closely associated with Quetzalcoatl ruled the Toltecs; his name was Topiltzin Ce Acatl Quetzalcoatl. This ruler was said to be the son of either the great Chichimeca warrior, Mixcoatl and the Culhuacano woman Chimalman, or of their descent.
It is believed that the Toltecs had a dualistic belief system. Quetzalcoatl's opposite was Tezcatlipoca, who, in one legend, sent Quetzalcoatl into exile. Alternatively, he left willingly on a raft of snakes, promising to return.
The Aztecs turned him into a symbol of dying and resurrection and a patron of priests. When the Aztecs adopted the culture of the Toltecs, they made twin gods of Tezcatlipoca and Quetzalcoatl, opposite and equal; Quetzalcoatl was also called White Tezcatlipoca, to contrast him to the black Tezcatlipoca. Together, they created the world; Tezcatlipoca lost his foot in that process.
Along with other gods, such as Tezcatlipoca and Tlaloc, Quetzalcoatl was called "Ipalnemohuani", a title reserved for the gods directly involved in the creation, which means "by whom we live". Because the name Ipalnemohuani is singular, this led to speculations that the Aztec were becoming monotheistic and all the main gods were only one.