Yes both theist and atheistic Satanism are considered religions. It doesn't matter if you agree or don't agree with it, whether they believe in a God(s) or Goddess(es); that's irreverent to the actual definition of a religion. Buddhism, for an example, we don't believe in any deity, but it is still accepted as a religion.
@SNP1, human based AND anti-Christian.
Also, I think you would like this debate that im in.
I haven't finished it, but if you'd like to PM me with some advice, I would greatly appreciate it.
i'm satanic atheist.... I don't really believe in god or devil(s) or anything, but i thought being satanic would be nice so i decided to convert, like two days ago, but i'm still kinda stuck on my atheist ways, so that's why i added an atheist after the satanic label