Much of true contemporary Liberalism is rooted in Christianity. Even when actual belief falls away, the forms of love, tolerance, charity, peace, and kindness remain. The religion was a means to this end, even if many of us cannot fathom just why an infinite God would choose to manifest his only Son in a specific place, at a specific time, to teach something, and be sacrificed on an altar by people committed to sacrifice, so that sins God alone specifies as sins could be atoned? I think this notion is silly.
But on a deeper level, it contains sacrifice as a chosen individual act. It includes committing oneself at a soul level to something foundationally important beyond ones tribe and ones family. You cannot separate these images from Christian dogma as a whole or, of course, Christ’s teachings as we have received them so many centuries later.