I’m not so much saying atheists as individuals are dogmatic, as I am that atheism is, as an ideology. Atheism takes a firmly negative stance on anything supernatural, asserting it does not exist, which is very different from asserting that it’s unknown. That premise alone makes atheism as dogmatic as religion.
For sure, there are all kinds of atheists, many very open minded and not at all dogmatic, just as there are some truly open minded religious folks.
The third type you mention butts into another kind of dogma: modern scientific dogma, which attempts to mash new information into an existing worldview instead of asking the questions it raises at the risk of throwing the old out the window. There’s science, the ideal of exploration and discovery, then there’s science we canonize into curriculum, never to be questioned — like evolution, Pangea, who built the pyramids. It just all seems to slide very easily into dogma.
I guess I honestly don’t understand the utility of atheism, over agnosticism. The path to knowledge begins with admitting you don’t know what you don’t know. Atheism begins by claiming to know with absolute certainty what does NOT exist. Why found an entire belief structure (which is what it is) on an absolute negative? It just all seems rather self-defeating.
I’m genuinely puzzled there aren’t fewer atheists and more agnostics. I also suspect a lot of atheists (the friendlier, open minded ones) may actually be agnostic in that they remain open to the possibility of the existence of the metaphysical and supernatural, but simply prefer the affiliation of atheists, who tend to be held up as sound rationalists by a society that’s sick of having a dusty old book shoved down their throats.