In the movie Annie Hall, written by Woody Allen, as a young boy, Alvy's mother, takes him to see a doctor as he appears to be dealing with some kind of depression. When the doctor asks Alvy what's up, Alvy explains that he just found out the universe is expanding, everything will spread out and go cold and die, therefore nothing he does matters, so he is not going to do anything anymore. Most people might see this as a joke, but I think Woody is trying to make a serious point.
The point here is about meaning. Imagine the universe did come out of nothingness, by the big bang. Next comes the universe, that is now expanding and will eventually die, and say the life of the entire universe then is 30 billion years, that might seem like a long time, but placed between the eternity past and the eternity future, then the 30 billion year life of the universe is just a single sentence, well, no, actually like a single word, no actually like a single letter, actually even smaller than a full stop in an entire library, but even that is an exaggeration, maybe the greatest exaggeration ever! So, then, to find meaning in a life of an individual of 80 years, that is infinity insignificant. If we lived the life of Gandhi a million times over, or an extreme Hitler where we gassed every man, woman and child alive, any of those actions would be totally meaningless in the big picture of all that is.
But now the atheists have to start their self-deception. They try to give the impersonal meaningless universe meaning. Just listen to them. In place of God, love, purpose they have these existential concepts of the survival of the herd, the advancement of mankind, the enjoyment of the beauty of nature etc...
So what's wrong with this? Well it's dishonest. It provides them with sanity and with that they can get up in the morning, get dressed, kiss their wives and children, go off to work and pretend it is real, but it isn't. There's no such thing as beauty or love, it's all relativity and even that is meaningless. The universe doesn't care if you succeed or fail, if you hate or love or whether or not you survive. It doesn't care if the herd survives or goes extinct. Nothing out of nothing. Keep going in this direction, enter that dark labyrinth and you will drown in the absurdity.
So to be an atheist then, you must be a nihilist. Anything else is a delusion, as great as the delusions of the Jehovah's Witnesses. In a self created, impersonal universe there cannot be any meaning. You are just a series of random events, you are no more valuable than a dog turd. Just as King Solomon said it is all in vain, totally meaningless.