dgludwig said:
"Because I'm not afraid to promote the causes I advocate."
Regretably, the matter has little to do with your rationale for advocacy.
It has to do with whatever rationale a prosecutor wants to attribute to your actions, particularly if that prosecutor aspires to a higher office.
Does anyone remember a prosecutor named Mike Nifong, who led the campaign to charge and convict the Duke Lacrosse team players of a rape, that it turns out never occurred? Nifong was disbarred and sentenced to jail for "a tragic rush to accuse", but he still ruined those kids' reputations in the process.
http://sports.espn.go.com/ncaa/news/story?id=3008460
If you're ever involved in a justifiable shooting (which hopefully will never happen,) there is a chance that something similar may happen to you.
If you have stickers that say "Protected by Smith & Wesson" or "Kill them all, let God sort them out" on your truck, etc., whatever your rationale may be could easily be overshadowed by someone who wants to portray you as a wild-eyed lunatic just praying for a chance to cap some unfortunate disenfranchised citizen.
IMHO, if you're carrying for self-defense the less said about it the better - both verbally as well as in terms of signs or symbols that let the world know.
Silence is prudence...
YMMV.