Boulainvilliers kept mediaeval history but changed his moral verdict on Muhammad

Evidence

I propose to consider most fully the case of Voltaire, but first to contrast his predecessor, Boulainvilliers, a more original historian, for whom the traditional sentiment about Islam, but not the traditional story, changes: for whom Muhammad retained the essentials of Christianity while purging the superfluous accretions; for whom Islam was not irrational, nor the Prophet an impostor; nevertheless, he rarely disagrees with the more discreet of his predecessors about what actually happened. He meant the same thing as they meant, only rejecting the word ‘imposture’ to describe it, a word which is indeed simply pejorative. The story that Muhammad constructed a religion in order to make himself world conqueror remained, only now the religion was reasonable, and the conqueror as admirable as Alexander or Caesar. — Norman Daniel, Islam and the West, 1607