Like many of his contemporaries, the mathematician and Anglican minister John Wallis (1616–1703) repeatedly made disparaging remarks about Roman Catholics, particularly the pope and the Jesuits. This paper considers how Wallis's anti-Catholic attitude affected his reception of ideas about nature and mathematics. A well-known example is his resistance to the adoption of the Gregorian calendar in England, which he claimed would be an implicit acknowledgement of the pope's authority. This was not an isolated case in Wallis's career. For instance, the same attitude is evident in his earliest publication, Truth Tried (1643), wherein he adopts a position on the metaphysics of time and place that explicitly opposes the doctrine of transubstantiation.
In addition, anti-Catholicism made Wallis more receptive to subjects that otherwise did not interest him, namely numerology and biblical prophecy. This helps to explain his decision to publish a Latin translation of Francis Potter's Interpretation of the Number 666 (1642), which Wallis seems to have appreciated mainly because of its argument that the pope is the Antichrist. These cases offer insights about Wallis's motivations as a natural philosopher and mathematician, and how they relate to anti-Catholicism in early modern English science more generally.