Here's a list of the religious societies that are a part of the University of Sydney Union Clubs and Societies Program:
"Australasian Union of Jewish Students [AUJS]
Catholic Asian Students Society [CASS]
Catholic Society of St. Peter [SSP]
Chinese Christian Fellowship [CCF]
Christian Students Uniting [CSU]
Conservatorium Christian Group [CCG]
Fellowship of Orthodox Christian University Students [FOCUS]
Hillsong Campus
Mandarin Bible Study [MBS]
Muslim Student's Association [SUMSA]
Orthodox Fellowship [SUOF]
Six-0-One [601]
Student Life
Unibodhi: The Buddhist Society [SU Buddhist Students Association]"
http://www.usuonline.com/Find_a_Club/find/?cat=6 [if you follow the link, you can get summaries of each club i believe). Seems to be a bit of choice there for christian societies.
edit: There's also the Evangelical Union on campus, it doesn't seem to be on the list though, not sure why.