I always considered myself agnostic leaning atheist. I consider leftism to be antithetical towards religion. All religions have a class structure to them, do priests, rabbis, or imams not exist? And what about marxism, is karl marx not venerated by some leftists in a weird atheist sort of way?
Catholic Worker organisations have done a lot of good work in the US starting just before the second world war up to modern day. Worth reading up on, i'm agnostic myself but I at least found it cool to see how religion can be used as a force for so many positive things when the people in charge aren't POS.