The latter helped me move past my attachment to Secular Humanism. When you accept the quite obvious facts that humans are not rational individually, and certainly not collectively and that Humanism, rather than being a common sense product of reason, is just the latest iteration of Christianity, humanism becomes just another myth.
The former made me realise that a bunch of people (myself included) overwhelmingly self-satisfied about their own rationality and independence of thought had uncritically swallowed any nonsense that made "religion" look bad and were actively resistant to any information or scholarship that went against these biases.