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.
I do often feel like we overcorrected after New Atheism, and also Catholicism gets too much of free pass on the anglo internet, which irks when you live somewhere where Catholic orgs are literally funding the hard right, BUT secularism is vitally important imo, and that means freedom of worship for everyone
And they'll use that freedom to worship as freedom to oppress. Would you give a Nazi the time of day in debating their beliefs?