Things that you normally don’t think about. For example if you tried to get a job and the owner refused to hire you, because you don’t believe in his religion, you can sue that they are discriminating. If you are atheist, that won’t work, because you don’t have a religion.

If a certain group claims to be offended by something, because it affects their religion, atheists have no say, because they have no religion.

There’s no tax exemptions, money that might be directed to religious institutions won’t go to atheist organizations, because again that’s not a religion and so on.

As for the other commenter’s, about putting Capitol displays and after school programs is meant to emphasize separation of church and state and religion in schools. The “abortion rituals” are for fighting recent SCOTUS ruling, that it apparently infringes their religious freedoms and prevents practicing their religion (kind of contra to Christians imposing their beliefs on others). Though, with current SCOTUS and states that are banning abortion, I don’t know if it does much.

They put cool shit up in state capitols (see: snaketivity), have “after school satan” clubs, abortion rituals. All sorts of shit to use the cover of religion to assert freedoms.