Perhaps one of the most fundamental and important messages which atheists need to communicate is that it's really OK not to believe in any gods. So many religious theists act like belief in some god and adherence to some religious belief system are the most important, fundamental, and necessary things that a person has to do in their lives. Irreligious atheists, however, can demonstrate through example that neither gods nor religions are necessary in any way.
We don't needs gods or religions to be moral, to be happy, to have purpose and meaning in our lives, to live well, to contribute to society, to be free, or anything else that makes life worthwhile and interesting. People's gods and religions may be important to them, but they aren't important to everyone and believers shouldn't expect them to be important to anyone else they encounter in their lives.
It really is OK not to believe. Not believing in any gods doesn't make a person less moral, less trustworthy, less interesting, less valuable, or less likely to do well in life. Only the prejudices, bigotry, and self-righteousness of religious believers creates problems for irreligious atheists, and this does far more to demonstrate the problems with religious theism than it does to reveal any drawbacks to irreligious atheism.