Atheism Plus' CausesFirst let's break down some of the causes listed by Atheism Plus, just so we are all talking about the same thing. I'm probably oversimplifying some of the causes here but please bear with me.
AtheismA person is an atheist if they do not believe in a god. In strict terms this means a lack of belief in any god. That's it.
Care for Social JusticeAction to have a lack of justice in our society that disadvantages or harms others rectified.
Support Women's RightsAction to have women treated as equals to men and to protect women from being harmed or disadvantaged simply for being female.
Protest RacismAction to have people of all races treated as equal and protect any one race from being harmed or disadvantaged simply for being of that race.
Fight Homophobia and TransphobiaAction to have homosexuals and transexuals treated as equals to heterosexuals and to protect them from being harmed or disadvantaged simply for not being hetrosexual.
Use Critical Thinking and SkepticismActively using logic and evidence in order to make rational decisions about claims in order to protect oneself from accepting falsehoods.
Atheism WRT CausesSome people contend that the above causes are natural outcomes of atheism. I'm not so inclined to agree. Lacking a belief in a god does not make one more likely to support these causes than would having a belief in said god.
If you support the above causes it's because you believe in supporting those causes for one reason or another. Certainly, most good people support one or more of the above be they theist or atheist.
Conversely, supporting one or more of these causes doesn't mean one is an atheist either. Possibly being involved with these causes may cause one to see things that will challenge one's faith, but it doesn't guarantee deconversion.
A Bit About MyselfI am a skeptic and critical thinker, I care about social justice, I support women's rights, I am against racism and I support Homosexuals and Transexuals in their cause for equality. I support the climate scientists and other environmental scientists in their fight against the forces of antiscience and corporate greed.
I'm also an atheist, none of the above causes increase or decrease my status as such. By Atheism Plus' Charter I could possibly be a member, but I don't know if I feel the need for another label.
Certainly, I think that any atheist involved in any of the above causes, where it's reasonably safe to do so*, should let the people they're working with know that they're atheist. Similarly, other atheists should support each other if they're working in these causes. Atheists should make it known when other atheists (again, when it's reasonably safe to do so*) are working in such causes so that the general public knows that many atheists are concerned about these things.
I think Atheism Plus is a good idea, but I don't know if it's necessary or even if it'll work. When Atheism Plus started there were some divisionary comments made, but to be fair they came from both sides. There have been atheists on both sides that haven't made things better and there are examples where atheists on both sides have been trying.
In the meantime, I'll keep reading, watching and listening. All the best whether you are an Atheist Plus member or not.
*Sometimes the atheist involved might have his or her safety compromised if the people they work with know they're atheists. Even if there aren't safety issues sometimes there are personal issues that could be complicated if one's atheism is exposed, especially if one isn't ready.