An understanding of the planet's various cultures and particularly their art. The history of human self-expression is bound up with religion, for various interesting reasons.
I personally have no use for this in my current course. I am interested in the harmful aspects of religion.
People thought you were learning about religion.
Those people would have understood your point if you had said that you are learning about atheism.
Anti-religionists do not believe in god, and wish to attack ideas connected with religion whether they have anything to do with believing in god or not. Anti-religionists are therefore willing to dismiss ideas simply because of who presents them rather than on their merits, and are thus subject to a pervasive ad-hominem bias.