I think there's a big difference between belief and dogma. While I agree there is lots of secular dogma, not all secular belief systems are dogmatic. If your belief system is constructed in a fundamentally evidence-based and emotionally-detached manner, then even your core beliefs should be open to challenge and question. I don't think most members of large institutionalized religions are willing to seriously entertain that their core tenets are wildly mistaken, otherwise they are in serious danger of becoming atheists.