In this case, the “thing” is the whole point of FFRF’s existence, to wit, freedom from religion and a Universe without God.
There’s no such thing.
What there is is a cobbling together of individuals who fancy themselves somehow elite and intellectually superior who make declarations intended to quash the free exercise of religion. Atheism is a religion, because it requires faith and belief. Meanwhile, all it takes is one little pizza parlor to declare that Jesus is Lord to make it all come crashing down for them.