you'll want to RP others dieties, so that you don't
A) heal people of deities that are clashing (Pyrtechon, Shadon, Branderback, Corath, Mist, Baraeon Ca'Duz, Kithairien, Xeen, Vierdri’ira, Grand -if you wanted to know) that will likely hurt ya... badly. And when you DO heal someone, you could/should RP getting hurt by it...
B) you can have long, intelligent (or not) conversations with people who have the same, or different deities. Imagine starting an argument with a Xeenite about how spoiled they are, and that they should come to your side and start serving a god that you devote your life to... (ok, pulled that outta my butt)
C) offend someone. I get offended. Alot. By either bards, (icky tweety birds) or persons of Toran because they go around SHOUTING that they SERVE TORAN and ALL MUST KNOW... ok, you should do that, and you should offend people by doing that. Just doing that will let ya know if people have the same diety, or if they hate ya... I just don't like it, but put up with it.