It is the question many people ask after hearing his story, and believers need not be afraid of it. Here is what historians agree on, what they still argue about, and what the Church has said.
What no one disputes. By the 1550s a chapel of Our Lady of Guadalupe stood at Tepeyac and drew large crowds. In 1556 a Franciscan preacher attacked the devotion from the pulpit, and Archbishop Alonso de Montúfar, who favored it, opened an inquiry. From then on the devotion grew without a break.
What is missing. No document securely dated to Juan Diego’s own lifetime names him. Bishop Zumárraga, at the center of the story, mentions neither the apparitions nor the image in any of his surviving writings. The first full accounts came more than a century later. A Mexico City priest, Father Sánchez, published one in Spanish in 1648, and Luis Laso de la Vega, the vicar of the shrine, published the Nahuatl Nican Mopohua the next year. Who wrote it is disputed. Some historians date it to the first half of the 1600s, perhaps from Laso de la Vega’s own pen. Many others, critics as well as defenders of the apparitions, place it in the 1500s and credit Antonio Valeriano, a Nahua scholar of that century, and the Vatican’s biography dates his text to 1556. The documents alone cannot yet decide it. In 1666 Church officials took sworn statements in Cuauhtitlán from elderly Indigenous witnesses, who repeated what older relatives had told them about Juan Diego and his holy life.
The quarrel of the 1990s. In 1996 Guillermo Schulenburg, abbot of the basilica since 1963, was quoted from an earlier interview with a Mexican Catholic magazine in which he had called Juan Diego a symbol rather than a real, historical person. The uproar ended with his resignation that same year, and he later joined other priests in a private letter to the Vatican arguing that Juan Diego’s existence had never been shown. In 1995 a small painted deerskin had come to light, now called the Codex Escalada after the Jesuit scholar who published it. It shows the apparition, names Cuauhtlatoatzin, and carries the date 1548, the year of his death. Laboratory tests in Mexico found its materials consistent with the sixteenth century, and a leading expert on the friar Bernardino de Sahagún, working from a copy, judged the signature on it to be his. Other scholars believe parts of it were added later, and some call it a forgery.
What the Church did. The Congregation for the Causes of Saints asked a commission of historians, led by the Church historian Fidel González Fernández, to look at the evidence again. On October 28, 1998, it reported that the documents and the long oral tradition were enough to show that Juan Diego had lived. Critics, among them the American historian and priest Stafford Poole, were not persuaded, and scholars still debate it. The Church canonized him in 2002.
A canonization declares that a person lived a holy life, is with God, and may be honored by the whole Church. It is not a ruling on every detail of an account first written down a century later. Apparitions belong to what the Church calls private revelation. Even those it has recognized stand outside the deposit of faith, so no Catholic is bound to accept one; yet such a gift can help believers live the Gospel more fully in their own time (Catechism, no. 67). And the Church has embraced this one for nearly five hundred years. It keeps the feast of Our Lady of Guadalupe across the Americas, and it has raised the man who carried her message to the altars. What it asks us to believe about Juan Diego is simple: God chose a humble man, and he now prays for us.