Oh my gosh. No one who has studied the history of theology can possibly argue that "little changed" between the Apostolic Age and Trent!!!!

Perhaps the most massive change in all of Christian history was from the Apostles to the great Greek Councils that establish the two natures of Christ and the Trinity as three-in-one. 

And perhaps the greatest delusion of modern Christianity is not recognizing that fact as fundamental to grasping that theology, understand as our response to revelation, is an evolving process, with new stuff constantly emerging from the old under the guidance of the Holy Spirit, the advocate Jesus promised would guide us into the future. 

Yeah, I know catechisms, including the "manual theology" that dominated pre-V2 seminary training, conveyed the opposite, but that was an impression based on faulty pedagogy, not a fact or even an alternate fact. Just a faulty impression overcome by actually studying the sources.