There is more than one kind of "liberal."
You know about political liberals. They probably vote for a Democrat or Green in an election. They disagree with political conservatives over how much taxes should be or how to address poverty or education.
I'm not interested in them. I want to talk about religious liberals.
Political liberals will read the same Bible as you or me and come away with more or less the same message; they may apply it differently, they may see different ways it should be put into practice, but we're reading the same Bible.
Religious liberals aren't reading the same Bible.
These are people who are uncomfortable with the supernatural. And so the Bible can't really be anything special. It's not inspired; it's merely the product of flawed men. And we probably don't even have what they really wrote.
So they feel free to pick and choose what parts matter.
They'll say religious conservatives do the same thing, but we have a reason, a system even, for "picking and choosing" — it's based on the work of Christ. (I recommend this video of a lecture by Voddie Baucham on the topic.)
They just throw out the parts they don't like.
So liberals will discount anything that suggests God is going to judge us. And, really, without judgment, who needs that whole "Jesus saves" thing? It's not like he died for anything; his life was simply cut short by people who didn't understand his message of peace. That's if he actually lived at all, not that it really matters.
Are homosexual relationships sinful? Of course not! Neither is pre-marital sex. Nothing that doesn't hurt other people is wrong. Hurt by their definition of hurt. As to why it's wrong to hurt other people, well, they'll hand wave why that's bad.
The only thing that matters to them is that God is love. Which is crazy. If you were going to throw out parts of the Bible, why would you keep the hardest part to believe? God is love? What in the world would make you think that apart from the Bible?
The problem with religious liberals is they claim to be Christians. They reject pretty much everything Christians believe. They say there is no sin, or if there is, it's not that big a deal (so long as you're nice). There's no repentance and no judgment to escape. There's no call to a life of holiness or sacrifice (except giving up fossil fuels). They say there's nothing special about Jesus. All while claiming to follow him.
If they called themselves Elbonians, it wouldn't be a problem. But they don't. They claim to be Christians. And we've got to figure out what to do about it.