Atheism ultimately submits to biology and amoral laws of nature, thought it dresses the idea up in fancy clothes. Without objective morality or truly free will, the impulse of the moment and the desires of the flesh are the ruling guide. God explained, "For they exchanged the truth of God for a lie, and worshiped and served the creature rather than the Creator." (Rom 1:25)
As Christians, we need to check ourselves, too. Sometimes we can be indulging in some fleshly behavior, and we can get defensive when exposed—but when confronted with the truth, we've got to take it, even if we don't like how it's delivered. Otherwise, we ourselves exchange truth for a lie. Let's take the truth even if it knocks us down a peg or two.
"For the entire Law is fulfilled in in this one word: "You shall love your neighbor as yourself."—Gal 5:14