The patron saint of priests, St. John Vianney, died Aug. 4, 1859. A century after the patron saint of priests, St. John Vianney, died on Aug. 4, 1859, Pope John XXIII reflected on the life of the saint and what it means to be a holy priest. In his encyclical, Pope John XXIII called St. John Vianney a model of priestly holiness. John Mary Vianney is a person who attracts and practically pushes all of us to these heights of the priestly life,” John XXIII further added. Pope John XXIII said Vianney, who was a member of the Third Order of St. Francis, clearly lived a life of poverty.