Have they never heard of the doctrine of original sin?
http://www.biblegateway.com/passage/?search=Psalms+51%3A5&version=HCSB
“Indeed, I was guilty when I was born;
I was sinful when my mother conceived me.”-Psalms 51:5
The doctrine of “original sin” is universally mocked by liberals, but it is probably the most inarguable religious doctrine of all. I mean, who can plausibly deny the human attraction to sin?