"Could you please cite when the Roman Catholic Church has ever changed its belief structure in 2000 years?"
Meatless Fridays? :)
On this topic, to name a just a couple of the hundreds or perhaps thousands, 1854 (adding the 'immaculate conception' of Mary) and 1950 (adding the 'bodily assumption of Mary'). The text of the papal documents themselves demonstrate by their terms that the respective popes were adding these rather unusual doctrines to the pantheon of RCC dogmas. Before the respective pronouncements, they were not part of the belief structure of the RCC (although a few individuals may have theretofore held to them personally), but afterward, they became mandatory parts of the belief structure of the RCC on pain of 'legal' punishment. That's what accretionism is.
Nothing wrong with believing that, just like there's nothing wrong with believing kaballah (sp?) or Mormonism either (apart from the fact they may not be true), but none are Biblical Christianity. "You takes your choice" -- and (I believe) you bet your eternal future on the efficacy of that choice. That's the only point.