When you see the big letter A it means the bearer is neither frightened nor ashamed to be identified as an atheist. Of course, for some of us, myself included, it’s no big deal. If somebody threatens me with violence because I don’t believe in a god, they will be arrested. In some places the police would assist the assailant!
The badge is really to encourage those who are under that kind of threat. I wouldn’t ask someone to display it if by doing so they risked their, or their family’s, safety or livelihood.
If, on the other hand, you can display it, that letter A will show other atheists that they are not alone, whatever the more strident religious people might say.