From Dragon Eye Atlas
Their origins are unclear and date back at least two centuries, and possibly longer, to times when the area was right at the edge between the Faith of Ikoyo and Faith of Nesra. It is named after Nemion Mahuman, the first member of the cult publicly hanged for membership in the heresy in 141 BV. Many both within and without the cult believe that he founded the movement, but some evidence points to a possible earlier existence.
The Mahuman Heresy is outlawed and membership has always been punished harshly, sometimes with death and sometimes with life imprisonment or forced labor in the Sumegaidau Mine. The last half century has seen more leniency towards cult members, however, mainly due to offensive activities of the cult dropping sharply after its internal revision in 11 AV. Today, some nobles even think about allowing the cult to exist, though the official priesthood would not hear of such talks and these ideas are traded behind closed doors among trusted friends only. The fact that even with the revision of its teachings the cult is still strongly blasphemous does not help its acceptance.
The cult attracts many curious or intellectual minds, among them a good number of priests and mages.
In total, membership is small with no reliable estimates of numbers, with most attempts at estimating tainted by political interests and likely to be either much too high or much too low. Those estimates that do exist range from about a thousand to almost ten thousand members. Evidence such as the number of members convicted with reasonably strong evidence suggest that the lower figures are probably closer to the truth.
There are two different types of members. A good portion of the heretics lives undetected amongst the regular population, pretending to be faithful followers of Ikoyo while conducting their darker rituals in hidden places. Occasionally such more or less improvised temples are found by chance. Some are in basements of seemingly reputable citizens, others in simple huts in the forest or in caves.
Another type of heretics are those who have been uncovered but managed to escape. With the support of still hidden members, they flee into the forests and band together, forming groups living off the land or supporting themselves through robbery and other crimes as well as donations from their still hidden friends, since they themselves have been stripped of all property, rights and titles for their crime of heresy.
The activity of these bandits is among the reasons that the population at large supports the prosecution of Mahuman Heretics.
The cult has no strict hierarchy, at least none that anyone outside the cult has knowledge of. There do seem to be higher and lower members, ranked mostly by their experience and length of membership, but no formal titles or other structures have been uncovered so far. With its low membership count, the heresy seems to be more informally than formally organized.
Not much is known about the teachings of the heresy except those fragments some members have divulged under torture and the few notes and books that were found. From these fragments it appears that the basic concept of the heresy resembles the teachings of Nesra with regards to the gods, but doubts that the six and ten are really divided. Instead, the heresy teaches, all the gods are uncaring and cruel, and all the good that humans see in them is there only by interpretation. For example, Kusmis could make every harvest plentiful, could she not? Since she does not, she is either evil or capricious. Similar arguments can be made about all the gods, both those considered good and those considered evil (if Qomis is the god of winter and there is no god of spring, why does winter ever end?).
Mahuman - or his predecessors if there were any - taught that man is left to his own devices and must rely on himself and not the gods. He also taught that all means of doing so are permitted as there are no higher powers to answer to. Necromancy, Black Magic, every kind of perversion or cruelty - all of these are things put into the world by the gods, so why should man not use them? If a Necromancer is not struck dead on the spot by the gods, so the argument goes, his actions cannot be too offensive to the gods.
The older teachings of the Heresy are full of greed and selfishness. With no good nor evil in the world, so they taught, everyone is for himself and should do whatever brings him pleasure or profit. Family is a random chance and society and its rules are deceit and control. Many of the early heretics were murderers, rapists, arsonists and worse, often in conjunction with dark magic or attempts to gain magical powers through blood sacrifices and other offenses.
In 11 AV, a secret congregation of high-ranking members unified and revised the teachings and took much of the edge off. While no specific practices or magics are outright forbidden, the cult now teaches that man must fight for himself, but consider the impact of his actions and how they may turn on him in the future. A view stronger towards a long-term strategy of survival in a cruel world now forms the core of the teachings, with many of the more offensive actions not disallowed, but discouraged due to the backlash they create.
This "softer" version of the heresy has found more acceptance amongst new members, and the cult seems to have grown again after having been reduced to - at least according to the confession of one member tortured and executed in 9 AV - just several hundred members.