Liberals, for unknown and illogical reasons, believe that peace and prosperity are the default condition, and insist that any deviation from this condition must be explained, with blame usually assigned to interference by evil conservatives.
In actual fact, of course, poverty and war are mankind's default conditions. Peace and prosperity, where they have existed, which has been only rarely in human history, do so only because they have been built and maintained via a great deal of effort.
I think this unconquerable and unquestioned belief that good things occur naturally, while bad things are produced only by human malevolence, explains most of why liberals believe and act as they do. All they have to do is use the power of the state to destroy the resistance of the bad people, and utopia will result.
Liberalism is essentially a secular, humanist movement. They blasphemously believe, most of them no doubt subconsciously, that we really can build heaven on earth, if only we were all more loving, more tolerant, more accepting, and so on. And this is very well and good and very difficult to argue against, until you realise the root of this argument is built upon a fundamentally incorrect appreciation of Human nature, and therefore it will fail. Not all liberals are atheists or agnostics of course. In fact probably most of them aren't, but its hard to square their utopian vision for Humanity with the clear descriptions of the depraved nature of Man propounded by Christianity (and, in fact, pretty much all the other major world religions too now I think on it).
I agree completely with your post, and in fact the theory you propound in paragraph three puts it very clearly and in a way I had not considered before. So thanks a lot for that.