What’s the actual difference between an atheist worldview and a liberal Christian worldview?

I’m genuinely curious where people draw the line. If both reject or reinterpret certain biblical teachings when they conflict with modern culture, what makes the underlying worldviews different?

For liberal Christians: what beliefs or teachings do you hold because Scripture teaches them, even when they go against modern cultural views?

And for atheists: what is the foundation for your moral beliefs and worldview if you don’t believe in God?
Not trying to start a fight. I’m interested in hearing where people think the real dividing line is.