Enlightenment thinkers preserved the medieval frame seeing Muhammad as religion’s inventor

Evidence

Even so, the more ‘Enlightened’ approach did not disturb the basic line established in the Middle Ages: Muhammad was seen as the inventor of a religion made up of bits and pieces acquired from round about; he was a deliberate deceiver, or at least a partly culpable deceiver, who established his religion by force. — Norman Daniel, Islam and the West, 1623