Anyobody else read A Song Of Ice And Fire??
It's a series of fantasy novels by George R. R. Martin.
Much of the story is about politics and struggle for power, but there's a character named Jon Snow, who sacrafices a normal life and goes to something called 'the wall', to defend the realm from basically supernatural and un-civilised pagans. He becomes part of a Brotherhood which sole purpose is defend the people.
Now this sounds nothing like religion, but Jon fundamentally gives up much of his life to serve a higher purpose and become a better person.