I divide these things up differently. Of course I distinguish between centrist liberals and more extreme left-wingers, calling the latter "progressives." But ultimately I think the political spectrum metaphor is misleading. As I argue, the main dichotomy is between humanism and animality. In demonizing their opponents, both extremes on the left and the right can lose respect for the inherent dignity of everyone. Utopian schemes reduce the masses to means needed to further some end. But progressives are closer to humanism than are even centrist conservatives, let alone neofascists, libertarians, Evangelicals, and so on.

And humanism doesn't derive simply from Christianity. It derives from ancient Greco-Roman philosophy which fed into esoteric Christianity (Gnosticism), via neo-Platonism, all of which go back to the Axial Age spiritual/existential reforms that spread globally via Alexander the Great's conquests.