The American Left, especially the Far-Left, gets stereotyped as being Atheist. This is reinforced by MSNBC at any point when they are talking about religion. Ditto, Salon, The Nation, the AlterNet or Bill Maher. But, there’s also a strong Religious Left in America and Sr. Simone Campbell is a perfect example of it.
The people of the Religious Left have very strong progressive and social democratic political tendencies. They believe that their religion tells them to look after people and their communities and that government has a strong role to play in this. They believe in social justice and that all Americans should have equal access to freedom and true equality.
You could make a good case that the Religious Left came of age in the 1950s and 1960s with the civil rights movement and Dr. Martin Luther King and his Southern Christian Leadership Conference. It was pushing for civil rights and equality for African-Americans but, by the late 1960s, they had won those battles and moved on to talking about and and pushing for social justice and giving the Federal Government a bigger role to see that more Americans have what they need to live well.
Not everyone on the Left is an atheist, as much as we get stereotyped that way. I come from an atheist family but I’m a liberal and an agnostic. There are liberal catholics and progressive protestants and even socialist christians. The problem with stereotypes is that even though they are all based on some truth, it’s never the whole truth. It’s a biased characterization of a group that others want the public to see. The popular religious characterization of the left is a perfect example of that.