Their hearts are a metaphor for . . . .
ego, selfishness, arrogance, rebellion, idolatry of their own wills . . .
. . . . to paraphrase . . . they likely already have their tickets to their eternal abode.
When describing the "force of nature" sort of God embraced by some Eastern religions, C.S. Lewis said it was like "an infinitely extended rice pudding." And that's how many liberals see the God of the Bible, as a love pudding who could never want anyone to follow any kind of rules. And no matter how clear his commandments and promises are, they wish to see him as a being who is largely unconcerned with morality, though they make an exception for the things that outrage them personally. That way, they get to live by "God's" laws and it just happens to match their own personal moral code. And if they hate their fellow man because he's a conservative, then that's OK, because "God" hates them too.