-ologists and -ologians

A theologian is someone who is versed in theology. They will probably know about stuff like theories of atonement, arguments for the existence of God, sources of authority in faith and so forth. They are less likely to know about the Mapuche deity in the form of a head with floppy ears which it uses to fly through the air and attack people, or the Great Rainbow Snake, and if it turns out they are conversant with such entities, they are likely to accord them a lower status than their own Jesus. On the whole, theologians tend to be emotionally involved in their discipline and lack the kind of detachment a "god expert" is likely to have.

Of course, typing anything about religion is a race against time and probability of it turning into a largely fruitless discussion increases exponentially, so let's drop that for now and simply observe that there are theologians, but there could also be "theologists", that is, people whose personal distance and approach is greater than the average theologian, and who take a more kind of Cartesian rather than Romantic approach to the matter.

Now abstract that distance and apply it to other ologies. Each ology has two sets of experts associated with it. On the one hand there are, for instance, the ecologists, who look at the relationships between different organisms in ecosystems in various habitats, approaching them in scientific terms. On the other, there are the ecologians, who are into stuff like the Gaia hypothesis, deep ecology and so forth. Then there are the psychologists, who are attached to experiments, studies and statistics, and the psychologians, who prefer qualitative research, psychodynamics and psychoanalysis. A third example: the sociologists are positivist, but the sociologians are more into post-structuralism, Marxism, Weber, Hayek or whatever.

Likewise with all -ologies. One set of people approaches them as BAs and MAs as 'twere, the other as BScs and MScs, and never the twain shall meet. Neither is considered inferior to the other, but they are entirely different subjects which happen to share the same field of study. It's also fine for an -ologian to moonlight as an -ologist and vice versa, but neither can be considered an expert in the other field. However, there is mutual respect between them and each recognises their lack of expertise in the other's subject.