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.
First rule of politics: learn to count.
Socialism needs power, not purity. Power comes from the size of the support base.
Socialism has historically been helped by religious support same way as it's been helped by nationalist support.
Fair enough, I just saw some comments in the thread for the Pope's death that really rubbed me the wrong way...