If there's one argument atheists don't understand, it's the moral argument. Every time it is raised, atheists consistently and reliably attack a straw man version of the argument. To this day, I have never found the exception.
One example of a straw man is that the moral argument states that no atheist can do good things unless they believe in God. This would obviously be a very foolish thing to say. Of course atheists can do good things without God. In fact, sometimes, they are better at it than religious people, and there is no shame in admitting that. So this isn't the argument. Nevertheless, atheists still ask "name just one good thing a believer can do that an atheist can't".
On the face of it, this seems to be an impossible challenge. This is why it so effectively gives the illusion of refuting the argument. There are very few good things a believer can do that an atheist cannot. A believer can give to charity, an atheist can give to charity. A believer can adopt a child, an atheist can adopt a child. A believer can pay his taxes, an atheist can pay his taxes. A believer can love God, an atheist... can't... love God.
And there you go, challenge answered. Loving God is a good thing a believer can do, but an atheist cannot. But this is where the atheist can say "but I don't believe in God, therefore I don't think it's a good thing to love God". And there you have the moral argument.
See, the very question "can you name one good thing a believer can do that an atheist can't?" assumes a standard of goodness that just cannot exist in the atheist worldview. If there is a God, good is what God says it is. It is His world, therefore good is when it functions as He intended, and evil is when it fails to do so. By contrast, an atheist has no standard of good beyond someone's opinion, be it their own, or some other moral source they have arbitrarily decided they agree with.
You should hopefully see the folly of the atheist here. By attacking the moral argument, they are ultimately proving the moral argument. By affirming that an objective standard of good exists, which allows atheists to be "good without God", they are affirming the premise that moral values are objective and binding over all people. So the question is, where do these moral standards come from? Why is it good to feed a homeless person, but evil to kill that same person? Christian answer: Because that homeless person, just like me, was made in the image of God, who has commanded charity and opposed murder. This person is my equal, and so I will treat him as such. The atheist cannot make the same assertion. He may be able to say "because I like charity" (assuming he even does) and "I don't like murder", but who has to obey the desires of another person? I like lemon ice cream, I don't like cranberry juice. Should lemon ice cream be free, but cranberry juice be banned?
What all of this ultimately comes down to is mankind's natural desire to actually be God. Every single one of us would rather write our own code of ethics and bind everyone else to it. Just as Adam in the garden, that involves ignoring God's commands, and maybe even His presence. But also, just as Adam in the garden, this is foolishness. The forbidden fruit causes death today as it did 6,000 years ago. And there is but one hope of salvation: God Himself.
Thankfully, He did provide such a hope. In the person of Jesus Christ, God punished all of our sins. By confessing Jesus as Lord, rather than ourselves, and believing He rose from the grave, we, too, can rise from the grave into an inheritance of eternal life. That is a good thing no atheist can do. But you don't have to be an atheist.