Historically, religious liberals have affirmed the presence of free will in humans. For example, Unitarians reacted against the predestination of Calvinism by affirming that humans could choose whether or not to do good, and their choice would affect whether or not they would go to heaven; and, being optimistic folks, chose to believe that humans would mostly choose to do good. In another example, Universalists reacted against Calvinism by declaring that all humans would get to go to heaven — a kind of radical predestination, or determinism, if you think about it — but nevertheless here in this life humans still have the capacity to choose goodness or wickedness; and some Universalists also affirmed that those humans who chose wickedness while alive would undergo a limited period of punishment after death. The details may vary, but religious liberals have long affirmed that humans could chose freely between goodness and wickedness.
During the Social Gospel era, religious liberals came to understand that wickedness could exist outside of the individual in social structures and wider society; sometimes humans do wicked things not because they freely chose to do those wicked things but because they were embedded in a social structure that was wicked. However, the Social Gospelers had no intention of doing away with the possibility of individual wickedness; they merely wished to point out another possible locus of wickedness; they pointed out that there is even more wickedness in the world than we had previously thought before.
Under the influence of the Social Gospel, and later the influence of humanistic psychology, and then liberation theologies, we religious liberals have become increasingly aware of the wickednesses that exist in society. We have been so attentive to social wickedness that we sometimes neglect the possibility for individual wickedness. But wickedness must still exist in individual humans: as long as we affirm a belief in in free will, we humans will have the option, as individuals, to be wicked.