Exactly what the title says, Christianity in all its various strains still stems from the horrendous old testament, and with all the awful shit that endorses, as well as with things like Calvinism and the general doomsday cult foundations in the religion, why do some people still act so charitably towards it? Christianity has proven itself to be a morally corrupt and oppressive institution at every turn. Or maybe I'm just too negative? 
EDIT Ok guys I get it this was rather reductionist, and I definitely was disregarding all the good that religious folks have done, and that religion has inspired people to do, but again over correcting into enthusiastic support for religion can also be problematic.
"Our cause?" Hexbear doesn't have a cause, it doesn't do anything. It has the least revolutionary potential of any leftist website I've ever used. I'm here because it's fun to shitpost sometimes.
IRL, yeah, there are better uses of your time than trying to convince people that astrology is bullshit. But having a materialist worldview and believing in astrology (or religion, for that matter) are contradictory, and getting rid of those brainworms via self-crit is something any communist should be trying to do.
I should mention that I'm not trying to portray myself as the perfect commie here, I still have my own brainworms. It's just the kind of thing that we should all be striving to get rid of.