Scholasticism introduced the notion that God was subject to human categorization and that his actions were understandable by the categories of human logic, which Protestant scholasticism continued.
The Scholastics set the ball rolling for the Nominalist reaction within the Catholic Church that later led to both Protestantism and to the Enlightenment centuries later.
The republican system in the United States had more to do with the rise of Pietism and the First Great Awakening, which altered the character of American Reformed Protestantism. Of course, both developed in a reaction to the changes following the 30 Years’ War.
Calvin’s Geneva and Puritan Massachusetts represent the true nature of unreformed Calvinism.