Thought experiment:
You see messaging from a believer in a religion you aren't in. It espouses the faith and encourages joining.
Is this "propaganda"?
It does seek to propagate an idea.
Must propaganda come from top-down in an existing power structure?
Must propaganda have an ulterior motive?
If not, what do you call 'honest' or 'grassroots' propaganda?
@Leucrotta fair enough; I do think you could meet a True Believer of Baha'i or Sikhism or Mormonism who just wants to save your soul, but it's hard to trust, isn't it? Whether it's advertisement for religion or products or sexuality, the desire to compel inherent in the advertising makes it suspicious to the recipient.
I suspect I found my word for 'propaganda but not government propaganda' just there.
Televisions propagandize McDonald's, missionaries advertise Jesus.