Deities from Other Worlds & Other Faiths

While the Three disagree about many things, they are united in one matter: They have no desire to share their power. They will go to any length to prevent any other god from arising. Several times they have joined together to prevent any mortal from rising even as far as the status of demi-god, even going as far as wiping out entire cities to prevent such ascensions.
While the worship of other gods is not expressly prohibited, the proselytizing of any other gods is forbidden. Clerics of other faiths caught preaching about their “false” gods are often arrested, imprisoned, found guilty of heresy and burned at the stake or beheaded, or both. Clerics of deities from other worlds are treated slightly more leniently than native groups such as druids or worshipers of the Dead Gods. Most of these "heathens" will generally not be outright killed so long as they don’t try to spread their faith.
It is thought by some who dare to speak of such things that the Three are trying not to draw attention to their world from the outside realms. Perhaps they fear the combined might of a full pantheon drawn to face them. They instead prefer to block up access to their world from elsewhere. They will also actively seek ways to thrust clerics from other worlds back where they came from. There is even rumor that there exists a guild of high level clerics and paladins drawn from followers of each of the Three whose job is to hunt down these off-worlders and use plane shift and other powerful spells to force them away from this world.
The followers of The Three, specifically the Inquisitors and the Heretic Hunters, are constantly on vigil and searching for groups of heathens that have become a threat. When they discover such threats, they are free to deal with such on their own if it is within their power. If a threat is too great for them to deal with alone, they will send to their leaders to request a Culling (see Cullings).

Opportunities

While these laws are strictly adhered to by the old world continents, the new world provides many untamed, wild and unexplored places where forbidden worshipers and groups can and do find hiding places to carry on their beliefs. So long as these groups avoid exposure in the more civilized areas of the land, they continue to survive.
It is said that some of the orc tribes that operate in the border lands between the civilized nations and the inner wilds will, from time to time, give sanctuary to some of these forbidden groups. The Inquisitors, however, have never found any evidence that this is true.