Because every opinion listed on Wiki is true? They do have a reoccuring theme of spirituality, but it is according to their own made up "Dark Carnival" mythos, which involves different types of sinners facing a "Jokers Card" figure which will deal them an appropriate eternal punishment. The only similarity it has to Christianity is that they are both ridiculous and fictional. It all boils down to how you live you life and getting what you deserve in the end, and that is where the similarity ends. The comparison is a common misconception however and I dont blame you for bringing it up.