Masius was born in Den Bommel around 1545 and studied at the University of Leuven, graduating Licentiate of Sacred Theology.

[1] During the Siege of 's-Hertogenbosch in 1601, he was active in his support of the city's defenders.

[1] Masius commissioned a catechism, the Catechismus voor de Catholijke jonckheijt des bisdoms van 's Hertoghenbosche, based on the Mechelen Catechism drafted by Lodewijk Makeblijde.

In February 1612, he ordered that this be the basis of all religious instruction in the parishes and schools of his diocese.

[2] On 9 and 10 October 1612, Masius presided at the second diocesan synod of 's-Hertogenbosch, the statutes of which were printed at Cologne in 1613.