Atheists make the case that God is a cruel, malevolent, genocidal maniac. And since that is so, it is up to the a rational, capable, godless mankind to figure out for himself, how to be civilized.
Here are examples of God of the Bible (Leviticus 19, 1-18) laying out the rules of love to mankind who is lost in hate, bullying, pettiness and greed.
“You shall not bear hatred for your brother in your heart.”
“You shall not curse the deaf, or put a stumbling block in front of the blind…”
“Take no revenge and cherish no grudge against your fellow countrymen.”
“You shall love your neighbor as yourself.”
Atheists deny God who taught mankind these rules of love and the Christian Western Civilization that wove them into their global civil society for the first time in human history.