Edict of Fontainebleau
The term was apparently introduced by John Calvin (1509–1564) in 1544 in his "Excuse à messieurs les Nicodemites". Since the French monarchy had increased its prosecution of heresy with the Edict of Fontainebleau (1540), it had become increasingly dangerous to profess dissident belief publicly, and refuge was being sought in emulating Nicodemus.