He was born in 1577, at Sigmarengen, a town in Germany, in the principality of Hoinvenzollen. The name of his father was John Rey. The saint was christened Mark, performed his studies in the university of Fribourg in Switzerland, and while he taught philosophy, commenced doctor of laws. He at that time never drank wine, and wore a hair-shirt. His modesty, meekness, chastity, and all other virtues, charmed all that had the happiness of his acquaintance. In 1604, he accompanied three young gentlemen of that country on their travels through the principal parts of Europe. During six years, which he continued in this employment, he never ceased to instil into them the most heroic and tender sentiments of piety. He received the holy sacrament very frequently, particularly on all the principal holidays: in every town where he came, he visited the hospitals and churches, passed several hours on his knees in the presence of the blessed sacrament, and gave to the poor sometimes the very clothes off his back. After this he practiced the law in quality of counsellor or advocate, at Colmar, in Alsace, with great reputation, but with greater virtue. Justice and religion directed all his actions. He scrupulously forbore all invectives, detractions, and whatever might affect the reputation of any adversary. His charity procured him the surname of counsellor and advocate for the poor: but the injustices of a colleague in protracting lawsuits for gain, and his finding fault with our saint for producing all his proofs for his clients in the beginning, in order to the quicker dispatch, gave him a disgust of a profession which was to many an occasion of sin, and determined him to enter among the Capuchin friars. He first received holy orders, and having said his first mass in their convent at Fribourg, on the feast of St. Francis, in 1612, he consecrated himself to God by taking the habit. The guardian gave him, in religion, the name of Fidelis, or Faithful, alluding to that text of the Apocalypse which promises a crown of life to him who shall continue faithful to the end. From that moment humiliations, macerations, and implicit obedience were his delight. He overcame temptations by discovering them to his director, and submitting to his advice with regard to his conduct under them. By his last will, he bequeathed his patrimony to the bishop's seminary, for the establishment of a fund for the support of poor students, to whom he also left his library; and gave the remainder of his substance to the poor.
In regard to dress and furniture, he always chose that for his own use which was the least valuable and convenient. He fasted Advent, Lent, and Vigils, on bread and water, with dried fruits, tasting nothing which had been dressed by fire. His life was a continued prayer and recollection, and at his devotions he seemed rather like an angel than a man. His earnest and perpetual petition to God was, that he would always preserve him from sin, and from falling into tepidity or sloth in his service. He sought the most abject and most painful employments even when superior; knowing that God exalts those highest who have here humbled themselves the lowest and the nearest to their own nothingness. He had no sooner finished his course of theology, than he was employed in preaching and in hearing confessions; and being sent superior to the convent of Weltkirchen, that town and many neighboring places were totally reformed by his zealous labors, and several Calvinists converted. The congregation de propaganda fide, sent to father Fidelis a commission to go and preach among the Grisons; and he was the first missionary that was sent into those parts after that people had embraced Calvinism. Eight other fathers of his order were his assistants, and labored in this mission under his direction. The Calvinists of that territory, being incensed at his attempt, loudly threatened his life, and he prepared himself for martyrdom on entering upon this new harvest. Ralph de Salis, and another Calvinist gentleman, were converted by his first conferences. The missionary penetrated into Pretigout, a small district of the Grisons, in 1622, on the feast of the Epiphany, and gained every day new conquests to Christ; the conversion of which souls ought to be regarded as more the fruit of the ardent prayers in which he passed great part of the nights, than of his sermons and conferences in the day. These wonderful effects of his apostolic zeal, whereof the bishop of Coire sent a large and full account to the congregation de propaganda, so enraged the Calvinists in that province, who had lately rebelled against the emperor. their sovereign, that they were determined to bear with them no longer. 'The holy father having notice of it, thought of nothing but preparing himself for his conflict, passing whole nights in fervent prayer before the blessed sacrament, or before his crucifix, and often prostrate on the ground. On the 24th of April, 1622, he made his confession to his companion with great compunction, said mass, and then preached at Gruch, a considerable borough. At the end of his sermon, which he delivered with more than ordinary fire, he stood silent on a sudden, with his eyes fixed on heaven, in an ecstasy, during some time. He foretold his death to several persons in the clearest terms, and subscribed his last letters in this manner: "Brother Fidelis, who will be shortly the food of worms." From Gruch he went to preach at Sevis, where, with great energy, he exhorted the Catholics to constancy in the faith. A Calvinist having discharged his musket at him in the church, the Catholics entreated him to leave the place. He answered, that death was his gain and his joy, and that he was ready to lay down his life in God's cause. On his road back to Gruch, he met twenty Calvinist soldiers with a minister at their head. They called him false prophet, and urged him to embrace their sect. He answered: "I am sent to you to confute, not to embrace your heresy. The Catholic religion is the faith of all ages, I fear not death." One of them beat him down to the ground by a stroke on the head with his backsword. The martyr rose again on his knees, and stretching out his arms in the form of a cross, said with a feeble voice "Pardon my enemies, O Lord: blinded by passion they know not what they do. Lord Jesus, have pity on me. Mary, mother of Jesus, assist me." Another stroke clove his skull, and he fell to the ground and lay wetering in his blood. The soldiers, not content with this, added many stabs in his body, and hacked his left leg, as they said, to punish him for his many journeys into those parts to preach to them. A Catholic woman lay concealed near the place during this butchery; and after the soldiers were gone, coming out to see the effects of it, found the martyr's eyes open, and fixed on the heavens. He died in 1622, the forty-fifth year of his age, and the tenth of his religious profession. He was buried by the Catholics the next day. The rebels were soon after defeated by the imperialists, an event which the martyr had foretold them. The minister was converted by this circumstance, and made a public abjuration of his heresy. After six months, the martyr's body was found incorrupt, but the head and left arm separate from the trunk. These being put into two cases, were translated from thence to the cathedral of Coire, at the earnest suit of the bishop, and laid under the high altar with great pomp; the remainder of the corpse was deposited in the Capuchin's church at Weltkirchen. Three miracles performed by his relics and intercession, out of three hundred and five produced, are inserted in the decree of his beatification, published by pope Benedict XIII., in 1729. Other miracles were proved, and the decree of his canonization was published by Benedict XIV., in 1746. The 24th of April is appointed the day of his festival, and his name is inserted in the Roman Martyrology. See the acts of his canonization: also his life, written by Dom. Placid, abbot of Weissenau, or Augia Brigantina, published by Dom. Bernard Pez, librarian in the famous abbey of Melch, in Austria, in his Bibliotheca Ascetica, t. 10, p. 403.
To contribute to the conversion of a soul from sin is something far more excellent than to raise a dead body to life. This must soon fall again a prey to death; and only recovers by such a miracle the enjoyment of the frail and empty goods of this world. But the soul which, from the death of sin, is raised to the life of grace, is immortal, and, from a slave of the devil and a firebrand of hell, passes to the inestimable dignity and privileges of a child of' God; by which divine adoption she is rescued out of the abyss of infinite misery, and exalted to the most sublime state of glory and happiness, in which all the treasures of grace and of heaven are her portion forever. Hunger, thirst, watchings, labors, and a thousand martyrdoms, ought to seem nothing to one employed in the sacred ministry, with the hopes of gaining but one sinner to Christ. Moreover, God himself will be his recompense, who is witness, and keeps a faithful account of all his fatigues and least sufferings.