This article shows that the conspicuous and consistent idiosyncrasy of Grotius's Biblical interpretation is an important part of his revolutionary effort to secularize natural law. In De iure praedae and related works, Grotius systematically deployed a range of exegetical techniques in order to demonstrate that the Bible, like all texts, is open to multiple interpretations and susceptible to hijacking by rival agendas. This strategy aimed to render the Bible inadmissible as evidence in legal disputes and political legitimacy claims. The consistent instrumentality of Grotius's use of the Bible in IPC cannot be dismissed as mere legalistic opportunism or described as an atheistic move. Rather, Grotius's exegetical strategy was motivated by pacifism and a desire to protect religion from politicization. The article positions this secularization strategy in the intellectual environment of the Leiden Circle, and shows how competing Catholic, Calvinist, and Mennonite political readings of the same key biblical passages during the Dutch-Iberian conflict provided the immediate occasion for writing IPC. In order to construct a natural law theory that was independent from, and therefore acceptable to, all religious sides, it was necessary to ensure that the Bible have no final word in law or politics, lest its invocation link disagreements to belief and thereby render them impossible to resolve.