There is a slight “glitch” built into Godus that allows you to get an unlimited number of followers without having to take up any extra space. First, you will need to build exactly one settlement. It should still be big enough to support the weight of a large stack of settlements, so mix as many of them in as possible.
Then, use God Seeding to surround the settlement with trees. Now, when you expand your settlement, the trees will force your settlement to expand upwards, and not outwards at all. Anything that’s solid will work in this capacity, but trees are the best thing to use because they take up so little space.
Now, with that surrounding batch of trees, your settlement will take up very little space, but it will build so far upward that it will turn into a skyscraper-looking thing with nearly unlimited height potential. In all respects, it will work just like any normal settlement will – it will just look much different than your other settlements.
Build more abodes, and keep absorbing them in over and over. If you want to literally gain unlimited followers from this, you will have to do it before building any farms or mines, or before populating any pre-existing farms and mines. Otherwise, you will be required to spend one wheat, one ore, or one wheat and one ore per new abode that you want to build.
Eventually, your settlement will literally run out of vertical space to expand, but when this happens, all that you have to do is do the same trick again with a new settlement. Eventually you’ll end up being able to build a skyscraper city that can hold massive populations. All this before even getting out of the Bronze Age! And of course, you can collect insanely high quantities of belief from them.