Atheism is an “ism.” So is Judaism, Catholicism, Protestantism, Mormonism, Baptism etc. Then you can get into racism, fascism, ageism, sexism, cubism but at the end of the day, they are all (according to the dictionary): a distinctive practice, system, or philosophy, typically a political ideology or an artistic movement. It doesn’t matter if Atheism is a religion or not (some would argue it is). It’s a question of ideology, philosophy and practice. One must decide on their own what that means in terms of environmental comfort.
I maintain that having a minority religion or no religion at all is experienced differently. It doesn’t give one a free pass to stereotype nor to prejudge anything without bothering to become informed. But please understand a person’s definition of what feels like force fed indoctrination can and does differ depending on background. It’s a sensitive topic for many and just because it feels vanilla and no big deal to one, doesn’t mean it is felt as vanilla and no big deal to the other.