Please answer a question about the following article about Separation of church and state in the United States:

Steven Waldman notes that; "The evangelicals provided the political muscle for the efforts of Madison and Jefferson, not merely because they wanted to block official churches but because they wanted to keep the spiritual and secular worlds apart." "Religious freedom resulted from an alliance of unlikely partners," writes the historian Frank Lambert in his book The Founding Fathers and the Place of Religion in America. "New Light evangelicals such as Isaac Bachus and John Leland joined forces with Deists and skeptics such as James Madison and Thomas Jefferson to fight for a complete separation of church and state."

What profession does Frank Lambert have?
historian