This is a great question. Let me make a few point of how psychology of religion can help the teacher of religion.
First, we need to realize that most of the people in the world is religious. This might be an unbelievable statement, but it is true. People thought that religious would decline, but we are seeing an explosion of it. Hence, it would be great to ask the question, "why." An angle of that psychology provides might also be very valuable.
Second, the way our minds work when it comes to religion can be a very fruitful topic of exploration. This alone would merit teacher of religion to know something about psychology.
Finally, when it comes to supernatural things, there is a fine line between sanity and insanity. This intersection is worth exploration as well.
To start with, Psychology of Religion helps the teacher of religion to adopt different techniques and methods of teaching for effective communication. The teacher of Religion has to make sure that the child is ready and receptive to inputs and stimuli. Hence a good knowledge of the developmental stage and age of child are important in deciding the curriculum, activites, relevance, instructional techniques, teaching methodology, et cetera. Psychology of Religion also helps the teacher of religion to study the ability, interests, intelligence needs and adopt different techniques of teaching for effective communication.
Finally, it helps the teacher of religion to apply the teaching and learning principles to achieve the objectives of education. Education is a purposive attempt to bring about desirable changes among the students. The objective of a classroom teacher is to bring about learning which encompasses long-term changes in behaviour & cognition. Some of the main learning theories include behaviorism, cognitivism, constructionism, et cetera, and each has contributed towards an understanding of human learning. They provide us with various models, approaches, tools and techniques to bring about effective teaching-learning. Teachers have to create the learning condition to provide knowledge and experiences to the students for the changes of behaviour. It is against this backdrop that I find the knowledge in Psychology of Religion very relevant to the teacher of Religion.
Allport, G. W. (1950.) The individual and his religion. New York, Macmillan.
Adler, A., & Jahn, E.(1933). Religion and Psychology. Frankfurt
Johnson, P. (1945). Psychology of Religion. New York: Abingdon-Cokesbury Press.
Meissner, W. (1984) Psychoanalysis and Religious Experience. London and New Haven, Yale University Press.