Called as Teacher, Preacher, and Celebrant
He never forgot his long years of dedication to the missions, nor did he abandon his mission work without pain. From 1938-1941, he found himself torn between the two subjects he loved, missions and liturgy, but was assigned to teach neither in the religion department at Notre Dame. Those were dark years for Michael Mathis. He himself described their resolution: "I came to the conclusion that a man cannot give full time to two sidelines. Hence I chose what I thought was important on the missions as at home." The missions' loss was the liturgy's gain. Then in his 50's, Mathis was too old and too busy to become a true liturgical scholar, and too enamored of the liturgy of Pius X to become a true liturgical reformer, but he was tireless in serving both scholarship and reform out of an unshakable conviction that the church's liturgy forms the church's life.
His guiding concern was catechetical: he was ardent in his commitment to the formation of the Christian consciousness and the Christian life of God's people through an authentic understanding of the liturgy. The Benedictine Godfrey Diekmann has characterized this relationship between liturgy and catechtetics as one of the unique contributions of the American liturgical movement.
Mathis pursued that concern with characteristic enthusiasm, working from small, inauspicious beginnings through a multitude of important liturgical projects, which would have exhausted many a person younger than he. When he was sent as chaplain to St. Joseph's Hospital, South Bend, in 1941, Mathis delighted in devoting all his spare hours, most of them late at night, to an earnest study of the liturgy and of it biblical and patristic sources. However, he soon came to the insight which was to animate all his later work: the liturgy must be not only well-studied but also well-celebrated to be fully understood