Since organized Atheists are the ones leading the charge, we'll put them at the front of the list.
Since atheism is essentially the result of skepticism applied to theism in particular, we'll put Skeptics next in line. Atheists are in an optimal position to learn how to apply critical thinking to all areas of life, having already worked through the more obvious fairy tales.
Lack of belief in god(s) also frees us up to reconceptualize our ethical framework from obeying divine dictates to reasoning for ourselves based on human needs and values. Hence, Secular Humanists must be included in the new big tent.
Finally, we should include the Anti-Theists, who go beyond passive unbelief to put themselves out there, doing the difficult and often thankless work of handing out red pills and freeing minds from the shackles of theistic dogma.
And, in line with the current thinking, we'll put a plus (+) sign at the end to indicate that we can add political causes on to our ever expanding big tent. So the final result will look like this:
Atheists, Skeptics, Secular Humanists, Anti-Theists, PLUS [selected political causes]
or just ASSHAT+ for short.
For SMS and Twitter purposes, it may be shortened even further: 3Þ+
Now, go forth and rebrand! Don't forget to stir up massive internet kerfuffles over which particular political causes are worthy of inclusion as we move forward and purge the non-progressives among from our ranks.