When we talk about a pseudoscience, one usually think about religion-related examples like creation science or astrology as an example of pseudoscience.
However, pseudoscience is often generated by scientists themselves when they try to make universal implications of their particular scientific knowledge. As an example, let me use scientism, which is the idea that all kinds of problems, including social, ethical and metaphysical problems, can be solved by means of scientific method.
The idea of scientism is based on an empirical observation that science has already helped us with a lot of issues, for instance, we learned how to cure a lot of diseases, to produce more food through new agricultural technologies and made human life longer.
At the same time, scientism avoids all kinds of counter-arguments. For example, when one point out that science also provided us with a number of completely new and even much more dangerous issues such as a possibility of nuclear war that can wipe out the humanity, proponents of scientism would answer that the problem is in politics or military decisions and not in the science itself. Therefore, from the point of view of Popper’s falsificationism, scientism effectively avoid «potential falsifiers» and can be regarded in the same group with theology or creation science.
Of course, falsificationism itself is very controversial idea that was criticized by Kuhn, Lakatos and many other authors, and I personally not support Popper’s position on demarcation of science and pseudoscience; so, let us try other demarcation criteria, for example, those of Thagard (see: Thagard P. Why Astrology Is a Pseudoscience?), according to whom a theory that is supposed to be a pseudoscience should be less progressive than alternative theories and face many unsolved problems, while its practitioners makes little effort to develop the theory towards solutions of the problems and are selective in considering confirmations and disconfirmations.
When it come to scientism, both of these criteria actually works well. Although we cannot be sure if scientism, formed in the late eighteenth century, is in any sense more progressive then other approaches, we can be sure that its practitioners who believe that scientism is a necessary part of science itself actually quite often are highly «selective in considering confirmations and disconfirmations» of the theory.
Of course, I should also mention that scientism can also be considered as non-scientific belief, and in this case it would not be a pseudoscience, of course. It can be regarded as a pseudoscience if and only if in is considered by its practitioners as a scientific fact/theory.
Today one can observe a rise of scientism in religious studies, and some authors even proclaimed the strictest versions of scientism which include such metaphysical claims as naturalism (Davidsen M.A. What is Wrong with Pagan Studies?; my ideas about the case: academia.edu). However, every time one says about the need of scientific study of religion or esotericism I have a lot of doubts because it seems like these people insist on necessity of implication of scientific methodology in humanities, which is a variant of scientism, which, in turn, seems to be non-scientific belief.
Therefore, instead of saying something like we should use scientific approaches in the study of esotericism, or we should use empirical approach in the study of esotericism, why do not say that we can use those approaches to provide a new perspective. But also we can try to use phenomenology of religion as methodology or, say, Hegelian idealism, Kantean transcendentalism or James’ «radical empiricism» and «pragmatism» — and see what new perspectives would be provided by those approaches.
Finally, the reason why humanities are so fascinating is that they are much less rigid and more pluralistic than the sciences, and it is important to keep them in those way.