This is one aspect of the left's enthusiasms that amuses me. They use the Darwinian theory of evolution (do remember that means a theory to explain the fact of evolution -- the fact that allele frequencies change over time, which is the definition of biological evolution) as an anti-Christian shibboleth, but don't really believe in the Darwinian account of human origins any more than a six-day literalist Baptist preacher from Tennessee does. What they really believe is Jean-Jacques Rousseau's account of human origins -- the "tabula rasa" in which where is no actual fixed human nature, only what society has "written" on us. Otherwise they would not spend so much time defending Darwinian dead-ends like homoeroticism, "transgenderism" and the interchangeability of men and women.
I'd like to see reporters ask Democrat candidates for office whether they believe in Darwinian evolution, then when they say "yes," confront them with the absurdity of a lot of their policy prescriptions that depend for their coherence on the rejection of any notion of fixed human nature. In truth as it bears on public policy, taking seriously the account of the Fall in Genesis or taking seriously the account of human origins offered by neo-Darwinism, both provide the requirement for policy to actually deal with human nature (and from the limited point of view of public policy, the fallen image of God given over to animal passions or the hairless ape who has attained reason sufficient to formulate quantum mechanics look awfully similar when compared the left's notion of humanity as a mass of victims of social conditioning who could be perfected if only laws and mores were changed to whatever the latest enthusiasm of the left happens to be.)