We all know that Monasteries evaporate quite early. That creates an "artificial" problem: if you conquer somebody AFTER that date, you have no chance at all to spread the religion that you will conquer (monasteries get ALWAYS destroyed, as they are culture buildings). Some people have proposed to make monasteries permanent, but that's unhistorical and unbalanced if they retain their science power. The way I see it, one of the following two must be done urgently:

A. Give the shrine the ability to produce missionairies.
B. Allow building a monastery even after it becomes obsolete. You lose the science, but you do it for the cash.

you may not be able to create more monastaries but the ones you have stay put. i keep making missonaries throughout the entire game as i always have new cities to spread my faith to that i couldnt reach before. also the speacil religious building spread the faith without missonaries.

you may not be able to create more monastaries but the ones you have stay put. i keep making missonaries throughout the entire game as i always have new cities to spread my faith to that i couldnt reach before. also the speacil religious building spread the faith without missonaries.

You forget something: to have monasteries you must first have a city with that religion. Probably this is true for the early ones, but this isn't always the case, for example, with Taoism, Christianity, or Islam. If the one that founded Islam had already another state religion with a holy city, he will NEVER send you an Islam missionary early enough.

Or perhaps you are playing on kind of Duel maps, where cities continue to be built until late in the game. In a pangea game you see very few cities built AFTER Islam is founded, so the chance to have a city with that religion approaches 0%.

You could build a televangelist unit with a McChurches.

The other solution is Organized Religion, if you really want to spread all religions that you take around, then that is the civic for you.

Although the idea of the Shrine allowing the building Missionaries seems interesting.