It’s especially hard because ALL of the logical, rational and scientific evidence is against them. Further, because of their “faith based” world view, they are more often defining themselves as agnostic, and yet at the same time denying their agnosticism.
What I experienced was that they describe themselfes as atheists, deny that atheism is a religion and when challenged to tell what they are actually believe ("I don't see (or know of ) any evidence, that's why I don't belief etc. "), make statements that meet the criteria of agnosticism.
I think on needs to distinguish two positions:
1.) "I do not believe there is a god". Which actually means "I believe there is no God".
2.) "I don't believe in god".
The first is definitely atheism
. The second could be agnosticism. Atheists usually try to appear convinced of position one, but when they are challenged with burden of proof, they switch to the second. A switch that is accompanied by the assertion that atheism isn't a religion, because "atheists don't believe in god or deities". But they are hardly disinterested agnostics or areligious. Otherwise they won't do any of the following. Doing things like arguing on forums against other religions, even start their own forums, societies, write books on their beliefs, etc. That's not areligious agnosticism, that's evangelical atheism!