Please go to your preferences page and make sure your "See Mature Topics" setting is set. Setting it to "Yes" means you see the Mature Topics forum (contains political and religious debates). Setting it to "No" means you do not see those threads.
Unless a forum or other web-based system is designed from the ground up to support SEO'ed URLs, it's usually a bad idea to implement them because programmers hard-code the script filenames. This is from the point of view of someone who designed a content management framework from the ground up in PHP with SEO-friendly urls in mind and then ported a popular bulletin board system (not vB, licensing issues) to use this system. It was... pure hell.