The research recalls the three greatest pandemics of the Christian Era: the Jus-tinian Plague, in the 6th century, the Black Death, in the 14th century and the Spanish Flu, in the 20th century. The nature of the disease, its origin, symptoms, routes and impacts are investigated in each sickness. It emphasizes how the Church went through each pandemic period, revealing its beliefs and interpretations for the plagues, the way it tried to ward off evil and the assistance it provided to the sick and mourning. The survey also reveals whether Christians have matured their responses to crises, whether liturgical aspects have been adapted and whether eschatological interpretations have undergone any changes. Following the chronological order in which the pestilences followed one another, the first chapter is devoted to the study of the Justinian Plague, revealing, for example, how the geographic and social context of the time contributed to the spread of diseases. The research advances to the Late Middle Ages, when Europe, Asia and Africa were ravaged by the Black Death, and shows, among other things, the frustrating medical and religious attempts to deal with the plague. Finally, the last chapter explores the greatest pandemic in history, the Spanish Flu, discussing its high lethality and the diverse way in which Christians from different denominations reacted.