At least some of the examples might be explained by _new groups_ taking over _old brands_, no? This would result in the group seemingly change its beliefs, when in reality, it has been replaced.
Take the cathlic church. Say some people realize that the geocentrism is wrong. You have the option of either splitting off and starting something from scratch; or, if you have the option, you launch a coup, and replace the people in the cathlic church, effectively changing the group, but still seeming as the "cathlic church" from anyone outside.
Take the cathlic church. Say some people realize that the geocentrism is wrong. You have the option of either splitting off and starting something from scratch; or, if you have the option, you launch a coup, and replace the people in the cathlic church, effectively changing the group, but still seeming as the "cathlic church" from anyone outside.