Read Psalm 137. Read it all the way through, including its final few lines:
O daughter of Babylon, you devastator!
Happy shall he be who requites you
with what you have done to us!
Happy shall he be who takes your little ones
and dashes them against the rock!”
Now ask yourself, “How can that be in the Bible?”
Then try to explain that to atheists.
The following is a link to my attempt at doing just this. It is published on Strange Notions, a popular website devoted to promoting dialogue between Catholics and atheists. The site bills itself as a “digital Areopagus,” echoing the famous dialogue of St. Paul with the Athenian philosophers in Acts 17. I recommend bookmarking it and perusing the resources blogger Brandon Vogt has made available which are geared toward helping us Catholics better defend the faith in the modern, digital world.