If Jesus's teachings about the sheep and the goats in Matthew 25 are to be believed then it is possible for atheists to be christian with a small c by performing good works and deeds and hence to achieve their 'Kingdom of Heaven' e.g,in their own lifetime, However..Christians with a large C who focus on faith rather than good deeds run the risk of being 'sent to Hell' e.g. at the Second Coming.
The important thing is to be decent to each other, and that's all that most reasonable religions are actually trying to say, albeit in highly convoluted ways.
I would agree that many churches effectively advocate evil by not condemning it, See for example my blog post
With all best wishes,