When he returned to Germany, he took his doctorate in law and began to practice as an advocate at Ensisheim in Upper Alsace. He gained a reputation for honesty and his refusal to use the vituperative language often then employed to level an opponent. His support of the poor led to the moniker "the Poor Man's Lawyer."
Repulsed by the unscrupulous measures used by his colleagues in practicing law, in 1612, he decided to enter the reformed Capuchin branch of the Franciscan Order, which his brother George had already joined. Mark Rey donated his wealth to the poor and to needy seminarians. After receiving holy orders, he took the name Fidelis. Upon completion of his theological course, he preached and heard confessions. Fidelis was successively appointed superior of Rheinfelden, Frieburg, and Feldkirch. During this last appointment, he reformed the town and outlying districts, and converted many Protestants. He also wrote a book of spiritual exercises that was translated into several languages.
His reputation grew due to his devotion to the sick, many of whom he cured during an epidemic. The bishop of Chur requested that his superiors send him, with eight other Capuchins, to preach among the Zwinglian Protestants in the Grisons of Switzerland. This was the first attempt since the Reformation to recover the area from heresy. Fidelis courageously pretended to disregard threats of violence. From the very beginning, the mission made inroads, and the newly established Congregation for the Spreading of the Faith formally appointed him leader of the Grison enterprise.
So great were his powers of preaching that he enjoyed tremendous success, which enraged his adversaries. They then worked to turn the peasants against him by representing him as an agent of the Austrian emperor, and avowing to him an intention to balk their national aspirations for independence. Forewarned, Fidelis spent several nights in prayer before the Blessed Sacrament preparing for death.
On April 24, 1622, he preached at Grüsch. He then travelled to Sewis, where, in the middle of a sermon on "One Lord, one faith, one baptism," a Protestant fired his musket at Fidelis. The bullet missed and lodged in a wall. In the following confusion the Austrian soldiers who were in the vicinity were attacked. When a Protestant offered to harbor Fidelis, the saint replied that his life was in God's hands. Fidelis attempted to return to Grüsch but was beset by opponents who demanded that he repudiate his faith. He refused, and as his murderers stabbed him with their weapons he called out to God to forgive them. (Another source says that one assassin's bullet missed him, but a second killed him.) A Zwinglian minister who was present was converted. The body of Fidelis now rests in Coira cathedral (Benedictines, Bentley, Encyclopedia, Farmer, Walsh, White). (courtesy of Catholic Matters)