In the Holy See's code of laws there had to be churches within all the cities of the Tanggulasi Empire. When the population of a city had reached a certain size, the size of the church had to be expanded correspondingly as well.
"During this campaign a sufficient number of slaves have to be deployed so that the Holy See would have to establish a church with Red Bishops in northern Qin. If this church gets destroyed the Holy See must rebuild it. This means that when I send a few hundred-thousand slaves over the pope must provide a corresponding level of support. This support is bottomless, otherwise, it will be akin to the Holy See refuting their own code of laws."