Liberal theology does not come from liberals thinking about religion, it emerges out of the disciplined process of how we tell these stories and engage those images. This means dealing with not just the stories, images and ideas that we like, but engaging the ones we don’t as well.
One of James Luther Adam’s (20th century liberal theologian) guiding principals for a free faith is a belief in continuing historical revelation. That means approaching the revelation of truth and meaning with both an openness to the future, which most liberals do well, and it also means a continuity with the past. This is what Adams referred to as a sense of length. In my former church we used to say it this way – in our faith the Bible is the beginning but not the end.