Why would someone think that if you don't believe in God you aren't capable of empathy?

I was idly following a friend’s FB post asking for advice on helping a refugee family from Syria get settled here. She was was willing to open her home to them for a time, and help them find work and lend whatever aid she could.

There were a lot of suggestions, as well as cautions. Then someone jumped in and said, “You don’t even believe in God. Why would you want to help anyone?”

It kind of floored me…and her. And led to this question.