Paine describes the difficult circumstances under which he wrote Age of Reason’s Part 1 in 1793, including his arrest and imprisonment in late December of that year. The French Revolution had descended into terror under Robespierre, and its bloodthirsty new leaders deemed Paine suspect, due in part to his English birth. Paine completed Part 1 a mere six hours before his arrest. He then languished in prison for nearly a year. His purpose in relating these circumstances is to explain that while writing Part 1 he lacked access to the Old and New Testaments, so he analyzed certain passages from memory, but for Part 2 he is working with both texts in front of him. Having reviewed each in substantial detail, he concludes that they are “much worse books than I had conceived” (66).

Paine analyzes the Old Testament book-by-book in what is Age of Reason’s lengthiest chapter by far. To believe the Bible (and he always means the Old Testament specifically when he refers to "the Bible”), Paine writes that he would have to believe in a God who sanctioned all manner of cruelty, and this alone would prevent him from accepting the Bible as God’s word.