Whether the nominee is liberal or progressive, Democrats will lose the general election if both sides don't support the selected candidate, AND the candidate they select has to be able to flip Ohio, Pennsylvania, and Wisconsin (all three) to beat Trump in the electoral college. Almost any of the candidates on display have a shot at winning the popular vote, but only a candidate who can flip those states that voted for Obama and then Trump back can win the presidency.
I'm not anti-Christian. I'm anti-stupid.