Changing religion

Hello everyone ,

I have a simple question, but I didn't find the anwser in the forums or anywhere.
Where/how can you change your religion/adapt the religion of someone else. I am currently playing a multiplayer game with a friend, and I went religion with Mayans, so my beliefs are better than his and I'm trying to convert his cities to my religion. When/how will it be possible for him to convert to my religion?

Missionaries and great prophets. The former will convert "agnostic" citizens to your religion, the latter both purges other religions and converts citizens..

Missionaries are about all there is. Religions do slowly diffuse into other religious cities, but the large pressure from other religions and their pops. will basically mean it has no effect.

Spam him with missionaries.

Also remember, he won't get all of the bonuses