There's plenty of militant and intolerant atheists, look at the rise of communism and the Soviet Union.
But is there an atheist dogma that says in plain text that atheist should discriminate against certain classes of people?
No, no there isn't. Contrast this with religious scriptures, that on their face plainly allow for slavery, oppression of women, and killing any sexual minorities or people who speak against the patriarchal authorities. To the extent religions no longer do this, it's because they're ignoring or interpreting away more and more of this plain text over time. This is secularism.
And if you look at Soviet policy, it arose out of the Church being tied up with the former corrupt government that had just been overthrown. This was due to cultural backlash, not some atheist commandment. In fact, they simply replaced all the old church institutions they'd destroyed with new church hierarchies that wouldn't challenge their new government, and now you see the Patriarch of the Russian Orthodox Church teaming up with Putin to
declare the war in Ukraine a divine cause.
Today, religion's net effect is holding back scientific progress, slowing moral progress, and impeding our work in building a peaceful and prosperous civilization. People can see this. And they're getting tired of it.