Why would he do such a thing?
The Age of Reason is a defense of Deism and a rejection of the world’s major monotheistic religions. It was published in three parts (1794, 1795, 1807).
Paine believed that a significant religious upheaval would follow the American and French Revolutions. In France, privileged orders such as monarchy and aristocracy had been toppled, and the established Catholic Church had not survived the onslaught.
As the French Revolution descended into revenge-induced violence, Paine feared the masses would succumb to nihilism and lose their humanity.
Paine completed Part 1 only hours before being arrested and sent to prison for nearly a year.
What was it in this man that caused him to risk his life to turn the face of men against their own church and God?