Sociology being my major in undergrad made me appreciate this series. It discusses the purpose of religion in our our society. On the level of the individual, it exists to satiate people's search for meaning, answers questions that science still fails to address, matters that are beyond our understanding. As Karl Marx puts it, it is the "opium of the masses."

On an institutional level, it serves to ensure social control. We have laws in place, and religion reinforces them in the form of introducing the concept of morality and guilt, of heaven and eternal damnation.

Not a lot of kdramas offer this kind of commentary, so I should say it's worth a watch.