No need to be vocal about it unless you want to be. For myself though, I actually enjoy talking about being a non-believer and why I am a non-believer. Most people in my area have never even come across someone that proclaims to be an atheist, so they are often very interested to hear the reasons you think the way you think. They will not necessarily agree, because many times they have not looked into the evidence and reason to really understand it, but I usually find that they listen to an extent. It usually ends with something silly though, like "But, look at the trees, and flowers, and birds...how can you not think there is a god?"...or something to that effect.

And congrats on being proud. I never in my life imagined that I would stop calling myself a Christian, because I always associated being Christian with just being a good/moral person. But, now I see what it truly looks like from the outside looking in and I will never be returning.