Heh. Why would blackflame people start in their own area when they are supposed to be hidden among the rest of the population, assuming the roles of normal citizens and faking the worship of the other gods? Not to mention that spawn points are not religion based, as well as Kadaikos being several weeks' (or even months) journey away from the Bronze doors if you know the way.
Also, Kadaikos is not some hellish place infested by evil blackflame followers. It is a 'normal' place filled with good people who are likely still being lead to believe that the black flame is a true god and savior. Remember, blackflame is not about evil and converting everything in its path to evil. It is a means to an end, even if those means are sometimes good and just things that make people's lives better.
Then again, everything about it could have been rewritten since I passed through. Which reminds me, are my books still in the BF library? I have not been in the game to check.