A heresiologist is someone who studies heresies. As the term is unfamiliar to many readers, I figured we might as well begin with at least defining terms before exploring more arcane and unfamiliar tasks. How does one become a student of heresies? In my case, as is often the case, it has been rather accidental. Perhaps there are some people who clearly aim at this identity intentionally, but I am not such a person. There are many things I prefer studying, but for whatever reason I end up reading a lot about heresies and being sought after as someone who is fairly knowledgeable about them. Like many things, this is a cycle that tends to reinforce itself. Having knowledge about heresies tends to give you the opportunity to gain more knowledge about them, and so on and so forth. When you know about heresies, people tend to go to you wanting to know what heresies their friends and relatives are flirting with, which tends to lead to more research into heresies and more knowledge and on it goes, without end.
Most people, it would seem, do not tend to read a great deal about heresies, but from time to time books relating to the subject come my way, and I read them thoughtfully if critically . To study heresies is to recognize that religious groups have boundaries outside of which one is not welcome. It is not my purpose here to discuss whether these boundaries are sound, only to state the fact that religious traditions that are concerned by orthodoxy–which is every religious tradition I am aware of–has some sort of gatekeepers who study what is outside the line so that others may enforce boundaries. Wherever doctrines are laid down there are going to be places outside the line. A statement about the nature of God, for example, makes every other position on the nature of God a heresy, and on it goes for other doctrines. And while there may be a great deal of tolerance for imperfect practice, there is likely to be less tolerance for those who consciously and deliberately have different beliefs about serious doctrines and who choose to state their differences loud and clear.
So, how does one become a heresiologist? At least in my knowledge, there is no application process nor any sort of interview process. For the most part, it is a fairly informal process from what I have seen. But that does not mean there is not a preparation for it nor a certain sort of person who is ideal for such a role. For one, such a person must be deeply interested in boundaries. People who find themselves in intellectual frontiers or dealing with people of different mindsets and beliefs are often well-suited to be heresiologists because of their knowledge and familiarity with the extent of options available. Not everyone is made more tolerant by wide exposure to different ways of thinking–some people become even more fierce about defending what they hold dear in the face of the threat of anarchy and chaos. Lest one think this is a problem merely among extremists, sadly that is not the case at all.
Just how common is this phenomenon? Let us count the ways. Anytime a political leader tries to define who is and who is not a legitimate member of their party because they are too moderate and don’t defend party orthodoxy enough, that person is acting in such a fashion. Anytime one reads a book or watches a video or listens to a radio show from a cult watcher who warns about certain religious groups, that person is serving in such a role. Anytime I am asked to read a particular book by someone or listen to a particular sermon message because someone thinks it might be off the reservation, so to speak, I am serving in that role, and that is more common than one might think. For example, I was once asked to listen to a sermon in a time of congregational crisis and the message quoted a poem that seemed to imply that Jesus Christ was a created being, a part of the ancient Arian heresy adopted by contemporary Jehovah’s Witnesses. Just this evening, shortly before typing this, I was asked by a close friend of mine to read a particular book of which three copies can be found nearby because it is a popular and heretical work. Despite my own lack of enthusiasm for reading the book previously, I now have reading it as somewhat of a mission.
So, let us recap. How does one become a heresiologist without really trying? First, it helps to have an interest in boundaries–setting them, defending them, tiptoeing close to them without crossing them, and snitching on others who transgress them. Add to this an interest in learning about others and their ways along with a tendency to be somewhat critical, and you are will on your way to becoming a heresiologist. If one develops a reputation for being knowledge about other ways of doctrine and religious practice, then one may very well be invited informally or even formally to be an expert on comparative religion, and one will have found to one’s surprise or maybe even chagrin that one has become a heresiologist simply by going about one’s business in a fairly ordinary way. Stranger things have happened to people who are less odd than I am, after all.
 See, for example: