I'm putting together a Pascal's wager piece of sorts, and wanted to see what modern religions think atheists deserve. So if Judaism pans out to be the one true religion, what'll happen to me (an atheist) after death?
depends whether you truly investigated the truth on this topic or whether you were just interested in writing papers. if the latter, tremendous burning regret. if the former, God will help you find it. And if He doesn't for whatever reason, though this is unlikely, then it's not your fault.
Here are some relevant quotes on this from a major Jewish philosophical work Chovos Halevavos
Gate of Repentance ch.5 (Pascal like consideration)
and another one from Gate 3 ch3 regarding one who neglects to follow the obligations dictated by his understanding such as an atheist who neglects his duty to fully investigate the truth as to whether there is a Creator and if yes, what does He want from me.
But if it is not one's fault for whatever reason, then the torah exempts one for liability of his actions,as the talmud derives in various places such as Nedarim 27a and as the Chovos Halevavos explains in Gate 5 ch.5 regarding not considering yourself better than a seemingly bad person.
As you can see it is not a single answer for everyone. Every case will be judged independently upstairs.
If someone believes in doing good because it is right and not merely for personal gain, then they do by definition believe in G-d, at least as Judaism defines it. They are simply defining their terms differently. Did you know that when the Romans would sentence a person to death for becoming a Jew, the crime was called, "atheism"? Since the Jewish G‑d cannot be seen or described, they considered this person to be without any god at all. Turns out that Judaism is closer to atheism than most people's theism. As Rabbi Sholom Dovber of Lubavitch once put it, "The G‑d the atheist doesn't believe in, I don't believe in either."