In his early years in Wolfenbüttel, Lessing published a series of writings about philosophy and religion directed against Enlightenment theology. The Enlightenment thinker took the side of dogmatic theology to attack Socinians, Neologists, and Deists. Lessing's position in these texts remains one of the most controversial issues in Lessing research to this day: why was the well-known freethinker a bitter enemy of rational Christianity? Lessing's opinion pieces written in favour of orthodoxy have been viewed as indecisive, tactical, and hypocritical. By reconstructing the Aristotelian tradition of the twofold philosophical manner of teaching, this study shows that Lessing, even in his theological writings, made use of both an exoteric and an esoteric art of writing, with the result that the key to understanding Lessing’s orthodoxy can be found in his vindications of Leibniz. Lessing’s defence of orthodoxy thus proves to be merely exoteric. The Enlightenment thinker defended dogmatic Lutheranism because the rationalization of Christianity compromised philosophy’s autonomy from theology. Only a strict separation between faith and reason, he believed, would guarantee the libertatem philosophandi.