Where do I go to find the roots of liberal morality?

Since liberalism is dominant in the media, academia, and Hollywood, liberals' holier-than-thou message, sent out on a near daily basis, is that they are the compassionate ones and conservatives are the evil ones.

I would be interested in knowing where to find the morality with which this compassion is built.

Do I look to Charles Darwin, whom liberalism points to as evidence that humans are the product of evolution and that the survival of the fittest is how nature guided us to fruition?  Many have said that National Socialism (Nazism) is rooted in Darwinism, that only the strongest survive and it's a "dog eat dog world."  Makes sense to me.

Do I look to Marx, who believed that we are all equal and that Heaven on Earth will be realized as the end point of history by simply implementing Marx's economic and social philosophy, following the "vanguard of the proletariat"?  George Orwell identified how this "vanguard" is seriously problematic in his novel Animal Farm, where some pigs are more equal than others.

How about Nietzsche, who infamously declared, "God is dead," and so the affairs of every individual are reduced to his or her will to power in getting what he wants?  This goes a long way in explaining the various iterations of today's Machiavellianism ("dog eat dog world") and value culture of ambition, success, and prosperity, not to mention all of the pettiness and schadenfreude that exist everywhere.

There is an old saying by the religious: "We are spiritual beings having a human experience."  Liberalism has inverted this to be "We are humans that may or may not have spiritual experiences (mostly not)."  In other words, it is rooted in the philosophical heritage of materialism, where man is the measure of all things.

So how exactly does one devise a moral system out of materialism?  The answer is, you don't.  Since liberalism is established now to be directly connected to materialism, it has to reject God and construct an artificial morality to be workable.

One could go on in trying to find the roots of liberal morality.  There's the trio of Jack Kerouac, William Burroughs, and Alan Ginsberg, the beat writers who paved the way for the nihilism and pseudo-liberation of the sixties that lives on today.  Or it could be found in the existentialism of Sartre or Heidegger, who held that all of being is reduced to simple existence, no more, no less, and that people have it in their power to create their own happiness (or unhappiness).  Putting individuals at the center of their own little universes created an illusion that's led to today's hyper-individualism and pervasive sense of self-importance (also commonly known as narcissism and egotism).  And one can't forget the research and published works of William Johnson and Virginia Masters that helped spark the sexual revolution, which continues to contribute to the downward spiral of self-destructiveness through the normalization of deviant social behavior in all kinds of manifestations.

I really would like to know when and how this compassionate liberal morality was constructed.  It is an edifice of smoke and mirrors, resting on a foundation of sand.