At the very end of Faith Conquers, Trevor Faith actually says something that appears to be Mundus Humanitas doctrine (as opposed to proverbs, swears, and snatches of scripture): that the Prophet Ahmilahk taught that free will was like a cloak of stone draped over the shoulders of a child, which had to be broken by the fist of fate – or something very close, I’ve not got my book handy at the moment. And then he finishes with, “There is only one real path, the river of fire. Everything else is an illusion.”
And Chris Moeller has talked about the imagery of the burning wheel http://burningwheel.org/forum/viewtopic.php?t=2998&start=14
And the rulebook says (p. 31)
This faith is a doctrine of fatalism and mystery. The Church believes everything is preordained. There is no way to alter one’s destiny. The only true way to live is to observe the natural order of things and live in harmony with fate’s plans. Resistance to this truth only begets misery. By accepting this mystery and one’s unknowable destiny, one can profit and even gain insight into one’s purpose. However, it does not bode well to be too presumptuous about one’s fate. It cannot truly be known. In the end, destiny will unfold as it desires, not as human beings try to make it or hope for it to occur. Only by observing the patterns of the Wheel of Fire—the symbol of Ahmilahk’s religion—can humanity hope to prosper. The flames of the wheel represent the living souls of all humanity.
Following fate doesn’t mean blindly stumbling around in the dark waiting to see what happens. By divining the patterns of fire on the wheel with guidance of the Mundus Humanitas’ Cotars, one can fulfill one’s destiny. Fate is a path to be followed with open eyes, not a road to blindly stumble down.
But other than that, we know almost nothing from either comics or game about what the Mundus Humanitas believes (or at least, it teaches people to believe). Almost all the visible details are clearly inspired by western Christianity of about 1100 to 1600 (high medieval and early Renaissance), with the burning wheel (itself an image of death and rebirth) used in place of the cross. The Hotok Cathedral is even gothic!
More fundamentally, there’s a clear “church and state” division, with a strict and elaborate ecclesiastical hierarchy existing alongside that of the secular (Imperial) government, not always easily, with its own armed forces, the right to select its own leaders, and problematic allegiance to a foreign power where church and state are combined (the Theocracy). The only time and place in human history where this ever existed was in Christian Europe. The Eastern Orthodox hierarchy was never so independent of the secular authority; the Jewish rabbinate and the Islamic ulema were never so formally and hierarchically structured, even among the Shia (witness how easily Moqtada al-Sadr has displaced Sistani as the key Shiite power broker in Iraq); Hindu and Buddhist monastic orders could prove tremendously independent and well-armed, but as far as I know never had a unifying structure above the individual monastery.
But clearly this isn’t a Christian doctrine. So what is it? If I Burn up an ardently devout character, what do I believe?