That's interesting because i can't off the top of my head think of an atheist who actually believes in god but is mad at him. Are you sure that, that's actually your experience and not a Christian meme?
Because i have spoken with many Christians who believe that atheists are just mad at god...no atheists though, who describe that as the reason for their atheism.
There are Atheists who became disillusioned with the church or with the values of their Christian communities. There are atheists who became atheists when they finally read the Bible for themselves and became convinced it was less than divine.
I mean...do you actually believe that Santa Claus is real but say that you don't believe in him because he didn't bring you that toy you wanted? Probably not, right? But that's the sort of argument you're making when you say atheists are "just mad at god for whatever reasons".
@TheOrionbeltseeker I have never spoke with an atheist who is angry at God. So I would say that the majority of atheistics aren't angry at God. What I do think is that the author of this post is angry at atheists.