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?
The official stance should be for socialists to stop alienating and being a jerk to people for their religion. They're the type of people who care more about being right or mentally superior correct opinion havers than they care about accomplishing anything. Saying, "but religious people often have regressive social views" is also another deflection because they're talking about the majority of the world. Yes, billions of people have regressive social views. Change their social views, but you're going to be even less successful at that if you're saying "YOU'RE A DUMB IGNORANT PEASANT YOUR CULTURE IS BAD GAZE UPON MY SUPERIORITY".