In 1617, he became a pastor at Hillegersberg, near Rotterdam. He resigned this position the following year, after he refused to take sides in a theological conflict in the Dutch Reformed Church, centering on faith out of free will as advocated by Jacobus Arminius or faith out of predestination, as defended by Junius' uncle Franciscus Gomarus. After his resignation, Junius elected to travel instead: he visited first France, and then moved to England, where in 1620 he was employed by Thomas Howard, earl of Arundel, as a tutor to his son, and later as librarian. It was for Arundel, an avid collector of Greek and Roman art objects, that Junius wrote his "De pictura veterum", a theoretical discussion of classical art and one of the cornerstones of the Neoclassical movement. Published in 1637 in Latin, it was followed by his own translations into English (1638) and Dutch (1641); the latter edition was written with a readership of artists in mind.