December 9 - 1531 - Juan Diego Sees a Vision of the Virgin Mary
Juan Diego was an Aztec man who converted to Christianity under the auspices of the Franciscans after the conquest of the Aztec Empire by Hernan Cortes. In 1531, he saw a vision of the Virgin Mary near Tepeyac hill. This vision would help spur Mexican Catholicism in the 16th century. Of course, it's also not entirely clear whether Juan Diego actually existed or even had an actual vision. What definitely happened is that Our Lady of Guadalupe, the apparition of the Virgin Mary, became central to Mexican Catholic belief and the shrine on Tepeyac hill became an important religious site. Largely this occured because the vision Juan Diego had was a perfect combination of Aztec beliefs and Spanish Catholic beliefs, creating a syntetic Catholicism in Central America.