My father (AIDS)
My sister (AIDS)
My uncle and my cousin and her best friend (AIDS, AIDS, AIDS)
The gays and the straights
And the white and the spades
Racism and race relations has been a theme in many musicals; some notable examples include South Pacific, Hairspray, and The Scottsboro Boys, though that's just the tip of the iceberg.
Wicked asks us to examine how we perceive things as good or evil, which I think is a pretty important theme. Kinky Boots is all about accepting yourself and others. Cliche but important, and I (obviously) think they did a good job.
I think The Book of Mormon is actually pro-religion. It makes fun of all of them. No discrimination. I think one of its major themes would be co-existence. And if you think about it, it also explores inner-culture/race relations, similar to The King & I.
I thought the theme of Book of Mormon was "whatever you make up that's comforting to you is fine" but Parker and Stone have questionable opinions anyways.
^ That too. There's really a lot of answers here. As there are with most great musicals. Hell, you can't even count all the themes of Into the Woods on two hands.
When choosing who should take you to the box social, go for the cute guy who has a lot of energy in the morning, not the creepy guy who sleeps in your aunt's barn
Great discount on theatre & musicals, definitely worth a look before you buy elsewhere. Always ends up being cheaper than competitors and they have amazing customer service. :)