On 24 August 1573 he resumed the pastorate in the previously Roman Catholic village of Hemsbach; where, with the consent of the congregation, he reconstructed the church along Reformed lines.
After the death of Ludwig VI, Johann Casimir, acting as regent of the Palatinate, called Pareus as teacher to the Collegium Sapientiae in September 1584.
Pareus began his literary activity with a tract against the doctrine of ubiquity, Methodus ubitquitariae controversiae (Neustadt, 1586).
Polemical matter accompanied his issue of the Neustadter Bibel, 1587, an edition of Luther's translation, with appended table of contents and superscriptions.
Pareus further contended against Johann Georg Siegwart in Sieg der Neustädtischen Bibel (Neustadt, 1591), and with Egidius Hunnius, in 1593-99, who accused him of the judaizing error of the Reformed party, with Clypeus veritatis catholicae de sacrosancta trinitate and Orthodoxus Calvinus.
In the Irenicum sive de unione et synodo evangelicorum liber votivus (Heidelberg, 1614-1615), he proposed a general synod of all Evangelicals to unite the Lutherans and the Calvinists, who, he represents, were surely at one in every essential.
This appeal of Pareus brought little response from his contemporaries, and his overture for peace was rejected by the Lutheran theologians Hutter and Siegwart.