Here's a list of what Randal Rauser thinks keeps atheists up at night from his blog. Let me provide brief answers.
This is not a problem for the atheist and I've never heard a single one tell me this keeps them up at night. No one is blessed or cursed under atheism. Our fortunes and failings are due to chance, by way of our genetics, our families, our environment, and innumerable other contingent factors. We accept that based on the evidence. We're thankful to the things that have actually mattered in our lives, which in most cases are other human beings.
2. Implications of nihilism.
If you view nihilism as there simply being no objective meaning or purpose to life, then the atheist is fine with that. It's only someone who feels that life is required to have objective meaning or purpose that is bothered by the idea of not having it. That's one of the reasons why religions try to make you emotionally dependent on them. They try to make you feel as if you need these things and then they try to offer you them. I explain this in my religion/heroin analogy. Atheism doesn't imply that there cannot be any meaning at all. Meaning and purpose in life are subjective, and many of us atheists find this a lot more comforting.
3. Failure to rebut moral relativism.
Some atheists are fine with the idea of moral relativism, but those who are not have plenty of moral philosophies to choose from that address the issue. But the question is, what kind of moral relativism are we talking about? Is it cultural relativism? Situational relativism? Even most theists acknowledge situational relativism. Also the Euthyphro dilemma addresses the claim that god gives us objective morality quite well.
4. Classical theism makes the strongest case for (what I would label) objective morality.
4. Classical theism makes the strongest case for (what I would label) objective morality.
If you define objective morality (which Randal didn't do on his post) in such a way that it can only be served by theism, then perhaps. The claim that only theism can make a strong case for objective morality is again challenged by the Euthyphro dilemma: Is something good because god commands it, or does god command it because it's good? The first part makes morality arbitrary, and the latter makes god irrelevant to what's good. The standard response is that god is the good – god is the ontological foundation of goodness because he is intrinsically loving, compassionate and fair, etc. But then we can ask, is god good because he has these properties or are these properties good because god has them? In order to avoid compromising god's sovereignty and admitting that these properties are good independently of god, the theist who wants to hold to the moral argument must say that these traits are good because god has them. But how is love, compassion, fairness or any other positive attribute good only because god has them? They would be good irrespective of god's existence, as would be evident by their effects. The theist would bear the burden of proof to demonstrate that they wouldn't be good without god, which I haven't yet seen anyone successfully achieve. Thus it's clear to me at least that objective moral values - if they exist at all - exist independently of god.
Plenty of false gods and false beliefs transform people in ways a Christian will "never experience." The way belief in god effects you is not an indicator that the god you believe in is real. Hope for an afterlife is just false conciliation, and most atheists reject this belief for exactly that reason (and because there's no good evidence for it). Atheists live in the here and now. We live for this life, not some fairy tale existence promised to come. Belief in an afterlife often devalues this life.