Please note the bolded.

No one will care if you don't drink if you participate and are a fun and festive person. If, however, you use it as an excuse to not go to things or stand around like a bump on a log, you won't be very well liked in your sorority.

Agree, and I'd add that being a fun person means not making any deal at all over either the fact that you're not drinking or the fact that others are.