Simply, there is no purpose for anything. Everything just is, and that's it.
And that's why the Problem of Evil is such a dilemma for atheists.
Oh, I know what you're thinking. You thought the Problem of Evil was a problem for Christians. You know, how can God be good and powerful, yet evil exists - it's the favorite question of twerps everywhere who've studied 'philosophy' for about twenty minutes and can't be bothered to think about it or look into what God himself says.
But I contend that the Problem of Evil is significantly greater for atheists. Namely: if there is no purpose, how can anything be evil?
And there is no doubt that they consider things to be evil. This hypocrisy is on full display every time there is a horrific event like Sandy Hook, or when we discover the wicked deeds of Jerry Sandusky, or when they pour contempt on evil folk like Westboro Baptist or Al Qaeda. In fact, even in the video above, you get the sense that he considers religious belief of any kind (other than materialism, of course) to be an evil thing, an opinion frequently expressed by the rabid atheists like Dawkins, the late Hitchens, et al.
They clearly and repeatedly declare things (and people!) to be evil. Yet according to their core belief, there can be no such thing as evil. Even the most vile, reprehensible person imaginable - think Hitler crossed with a pedophile crossed with Urkel - cannot rightly be charged with evil, if they believe what they claim.
On what basis could he? He can't be accused of acting contrary to our purpose, since there isn't one. Causing his victims to suffer? Doesn't matter - they're just organized molecules, and they just would have decayed into disorganized molecules at some point anyway; does it really make a difference how they get there? All is meaningless; all will be forgotten when we're dead. Same thing with the sufferings of their loved ones. Surely they can't be evil for breaking the law or acting against societal norms - those are just made up by groups of organized molecules who will all be dead soon anyway, so see above.
And so it goes with any other reason they can come up with. If we're nothing but matter, and there's no purpose for anything, then there is no meaning, and therefore there can be no good or evil. If everything just is without purpose, then everything we do just is without significance. And every time atheists act like something is good or evil, they reveal their hypocrisy - they don't believe what they shout from the mountaintops.
So the Problem of Evil for atheists boils down to this. The very concept of evil requires a standard against which good and evil can be judged, and the existence of a standard requires someone to establish that standard - and judge by it. As much as they may try to suppress this truth and deny it, their (sometimes correct) protestations against evil show that they know it.
Through all the bluster about our meaningless existence, their actions show that they know that there is sin. And their problem is that one day sin will be finally judged. But God is gracious and has given a perfect solution. May they stop the hypocrisy, acknowledge the truth, and grasp the only cure to the sin that kills us.