A name commonly thrown around when discussion liberal Christianity is Paul Tillich, famed for a Christian version of something like Heidegger's philosophy of religion. Here's a very long and slow-to-get-going (not to mention very dark on my screen) interview with him:
Watch on youtube.
In this first clip (around 5 minutes in), he describes how tragedy shaped his philosophy (interestingly, he seems to equate "idealism" as having a positive, optimistic outlook with the metaphysical idealism of Hegel, Fichte, etc.). Around 8 minutes in, he compares philosophizing in German vs. English (with a pretty positive assessment of English as better enabling analytic clarity).
In the 2nd clip, he talks a bit about Christian socialism in Germany. Around 3:45 in, he discusses his influences, citing not only German idealism but Heraclitus and Parmenides as being key. His biggest influence was Schelling, whom he credits as anticipating modern existentialism. He also, surprisingly, cites Hamlet as providing an early model of existentialism for him.
In the 3rd clip, he gets into the relationship between Christianity and the various existentialist figures (Sartre, Nietzsche). He says that Christianity can make use of the results of any tradition and not essentially tied to any of them (which is hard for me to understand unless his views are something like Schleiermacher's)
It's not until clip 4 when Tillich gets around to talking about what he thinks the religion and philosophy is: both are about addressing the question of the meaning of "my life and life generally." Around 1:40 he starts talking about the notion of "spirit," which sounds straight from Hegel, and he describes morality as "the realization of oneself as a person," not following preexisting external moral laws (which he calls "moralism," not morality). Following laws "instead of considering them as expressions of what we human beings essentially are and thus should be" is distortion of morality. We invent morality; it is an expression of us. This sounds much more like Nietzsche than Kant, and sure enough, the interviewers ask Tillich what keeps us in line if we're not following rules. Tillich's response is "love," which is very much in the spirit of Schleiermacher even if S. explicitly buys into Kantian ethics. Inverting Kant, Tillich says that even the strictest obedience to moral law doesn't count as truly moral behavior if it doesn't come out of love as a reaction to a concrete situation (meaning that the right way to respond can't be captured in rules, which can't capture all the specific possible situations). Rules like those elaborated in the Sermon on the Mount should be taken as expressing the wisdom of human experience: we should take them as good advice that needs to be absorbed and used to feed our own free moral expressions.
All in all, this is a pretty interesting if slow-moving interview (it assumes you already know who Tillich is and have a reason to care about what he haw to say), though unfortunately it displays no philosophical acumen on the part of the questioners (unlike, say, those much more pleasant Bryan McGee interviews).