You might think of it as the dogma part of the sorority/fraternity experience. In our terms it was the recital of the secret stuff during chapter meetings. It's like in church where there are a series of prayers said by the entire congregation. A statement of faith, if you will.
And the goat sacrifice.
On a related note, I've always thought it was too bad for the ritual to be secret until you are in. I have to assume that the stuff we say are our guiding principles vary, from a little to a lot, from other sororities. What if I'd gotten in and went "Hey, I didn't know there was going to be goat sacrifices! I want out!" I've never heard of someone quitting over the ritual, but I wonder if it ever does happen.