The Demon-Fighter of France

A funny thing--my great-uncle worked in the Army as a helicopter pilot with a man who was descended from Jean Vianney.  Every so often, the man would wander around the helicopters, "blessing" all and sundry.  Along the same lines, one of the English teachers at my highschool appears to have married into/been a part of the family of St. Catherine of Siena.  Random coolness.

Anyway:

...Although many considered him unfit for the priesthood, he revived the crushed faith of an impoverished village and often spent eighteen hours a day hearing confessions, often sleeping only an hour or two each night.

As the reputation of this holy man of God spread, pilgrims began to seek him out, sometimes waiting days for him to hear their confession, heal their illnesses, and speak directly to their deepest needs. But not everyone was so pleased. This priest began to be attacked, sometimes physically and, at other times, emotionally and psychologically. He was verbally mocked, scorned, and abused. At night he was subjected to loud and violent noises for hours on end. He was pulled from bed in the middle of the night and, on one occasion, his bed was set on fire.

Despite this constant abuse, the priest never called the police or requested security. It wouldn’t have mattered, for the abuse and taunts did not come from another human, but from Satan. The priest, of course, was St. John Vianney (1786-1859), the Curé of Ars, whose feast is celebrated August 4.

Although rightly renowned for his holiness, asceticism, and spiritual insight, the Curé of Ars was also remarkable for his courage and steadiness in the face of the Devil. For some thirty-five years (1824-1858) Satan assaulted the Saint in a nearly endless number of ways, seeking to break the will and resolve of the great man of God: making harrowing noises, singing in a wicked voice, meowing like a cat, or shouting, "Vianney! Vianney! Potato eater!"

...It is said that the Devil told St. John Vianney, "If there were three such priests as you, my kingdom would be ruined." The Saint, for his part, developed a remarkable sense of humor about the supernatural assaults, saying, "Oh! the grappin" – his nickname for the Devil – "and myself? We are almost chums."

It's not likely that we'll ever have to struggle with Satan the way St. John Vianney did, but we should be familiar with who he is and what he does – and why he must be resisted. That begins with acknowledging that he exists and that he wants to destroy us. It means knowing that although he is powerful, Satan is limited and he is already defeated (CCC 2852, 2864). Imagine a person so dedicated to God that he becomes likes St. John Vianney. That saint could be you.

The article has an excellent overview of Catholic doctrine and Scripture on the existence and nature of the Devil.