If you call yourself a something-ist, this implies that the something is important to you. We can reasonably suppose that you think about it a lot and talk about it readily.
It's a bit odd to call yourself an atheist, as it seems to imply you're obsessed with something you don't believe in.
I don't call myself an atheist, I'm just not religious; and neither were my parents nor grandparents.
I suppose people must believe in religion either because they have evidence that it's true, or because they feel some irrational compulsion to believe without evidence. Myself, I've never seen the evidence nor felt the compulsion. I read science fiction and fantasy for entertainment, but in real life I've never been tempted to believe in gods, fairies, ghosts, or other fantastic beings; and I remain greatly puzzled at the large number of people in the modern world who still seem able to believe in such things.
See also my selection of quotes on religion.