Holy Moly. I can't imagine just listening to BR and listening to singles. The songs are not very long and it would seem really disjunct.
Just get Suffer and Recipie for Hate, and Generator (all albums) and work from there.
I still think that "American Jesus" is the quintessential Bad Religion song, but then again, it was A) the first BR song I heard and B) it appeals to my god-hating and my American-way-of-life hating nature.