The author is trying too hard to create a story. Is it possible that Abraham, Moses, David, Jesus, Paul and others, just in the religious community, have had a bigger impact on the US than Calvin? Then we could mention Locke and many others in the political and philosophical community.
The argument from some scholars (which I agree with as an Intellectual History major myself) is that the role of the Protestant Reformation in forging the philosophical backbone of America’s founding goes highly unrecognized by today’s mainstream scholarship. Locke and Enlightenment “rationality” took second place. The latter had more of an impact on the French Revolution and modern Europe.
The distinction between Protestantism and Enlightenment secularism is the dividing line between U.S. and European civic culture to this day.