Why do humans need religion or spirituality? Is it rooted in the ignorance about or fear of the natural phenomena? Or the answers lie in a more sophisticated level, such as the existential search for meanings and values? The course will start with (1) a survey on the classical theories in Psychology of Religion proposed by Sigmund Freud and Carl Gustav Jung, and then (2) examine the current theoretical advancement in the field from the perspectives of Developmental Psychology, Cognitive Science and Social Psychology; and (3) the related issues of mental health, practices of mindfulness as well as religious terrorism.