How did Johan van Oldenbarnevelt become interested in Protestantism?

Johan van Oldenbarnevelt’s interest in Protestantism first began to germinate during his time as a student in Heidelberg, where he studied law.1

While he later became a member of the Reformed Church, his approach to religion was characterized by a desire for a latitudinarian church—one that was based on the Reformation but sufficiently broad in its dogma to accommodate those who had moved away from Roman obedience. Throughout his career, he championed the ideal of religious tolerance, often clashing with strict Gomarist Calvinists who sought to establish a church independent of civil authority.2