Why Atheism Can't Explain Evil

After national tragedies like the Las Vegas shooting, people sometimes question God and His existence in light of such evil. In truth, you cannot even define "good" or "evil" unless you have the standard God provides. Atheism, and it's ideological cousin Evolution, cannot consistently call an act evil since man is nothing more than a chaotic collection of evolved molecules. Christianity alone explains and makes sense of the world around us. All other belief systems, including Atheism, are not only false; but irrational.