Actually, the term comes from the Roman Catholic church - their propaganda office.

QUOTE; On January 6, 1622 Gregory XV erected the Congregation de Propaganda Fide as central and supreme organ for the propagation of the faith to aim at the union of the Orthodox and Protestant Churches and to promote and organize the mission among non-Christians.

https://en.wikipedia.org/wiki/Congregation_for_the_Evangelization_of_Peoples#:

Edward Bernays, as per the article, invented it. :)