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.
Because there are billions of Christians on planet earth and that's not changing anytime soon. We also have Islam and Judaism communities too. I'm also going to make a bold prediction that the youth are going to turn towards religion in the coming years and break the trend of rising non belief. Just look at the USA, Christianity was on a decline until 2019, but then numbers stabilised. I expect that the numbers will now rise.
And before anyone says anything about how I'm some religious person, I'm an atheist, but I'm calling it how I see it.
It's already rising.
British church attendance has risen by 50% in the last 6 years. The two largest groups that attendance has grown for are 65+ and 18-24 year olds (Gen Z).
https://www.biblesociety.org.uk/research/quiet-revival
People seek community and safety. We shouldn't let the forces of reaction pollute their minds with idiocy and hatred.