How do we decide who deserves a place in history? Generations of devoted American history buffs have spent countless hours reading and writing long books about the American Revolution without ever having come across the name of Dr. Thomas Young. Yet it was Young who came up with the idea for the original tea party—the one in Boston Harbor. And he went on from there to help kick off the Revolution in Pennsylvania, co-write the first modern constitution, and name the state of Vermont. The reason he isn’t well remembered today is just this: The grandfather of today’s Tea Party was an atheist in all but name.

Thomas Young was born in 1731 in upstate New York. The child of impoverished Irish immigrants, he grew up in a log cabin without the benefit of a formal education. But he was an avid reader who began collecting books at a young age and eventually amassed one of the finest personal libraries in New England. As a teenager, he taught himself enough to become a successful doctor.

In 1764, at the age of 33, Young published his first screed championing the rights of “the common people” of the colonies against the injustices of imperial rule. In 1765, while living in Albany, he played a starring role in the protests against the newly passed Stamp Act, which put a tax on printed colonial goods, including newspapers, pamphlets and playing cards, and rose to the leadership of the local chapter of the Sons of Liberty. In 1766, Young moved to Boston to join with the radical faction gathering around James Otis and Samuel Adams. He rapidly established himself as the group’s most militant voice in the local newspapers and the go-to man whenever a rabble stood in need of rousing. Massachusetts Governor Thomas Hutchinson, a Boston-born loyalist, regularly named Young as one of the most dangerous men in town.

In 1772, together with his fellow radicals, Young founded the Boston Committee of Correspondence. Formally, it was just a letter-writing extension of the traditional Town Meeting, an assembly of local citizens; informally, it was the people’s liberation organization of Boston. “What an engine!” John Adams exclaimed many years later. “The history of the United States can never be written” until one has inquired into the activities of the Boston Committee of Correspondence, he said. “France imitated it, and produced a revolution. England and Scotland were upon the point of imitating it, in order to produce another revolution. … The history of the past 30 years is a sufficient commentary upon it.” And Young’s handwriting was all over the project—quite literally. In the files now held in the archives of the New York Public Library, his distinctive script appears on dozens of unsigned pages of committee papers—more than any other committee member—including on parts of a draft of the 1772 declaration of the “Rights of the Colonists” that Adams later suggested was one of the models for the Declaration of Independence...