So not looking to start a fight, but asking two honest questions.
1) How far can the pope move away from traditional Catholic teachings and still be considered “not a heretic”?
2) If a pope does go rouge, what controls does the Church have to bring him back in line with traditional teachings?
Full disclosure - I am a Baptist by upbringing and consider myself a conservative Protestant (non-denominational) now.
It’s a difficult, and to some extent unprecedented, situation. There have been bad popes before: adulterers, scoundrels, near-heretics. But there were counter-weights that limited the scope of papal power and prevented the Church from completely going off the rails. Specifically, the Christian monarchs of Europe limited the damage of bad popes, as they were involved with and/or controlled the selection of bishops in their own countries or principalities. Also, at one time, the King of France, the King of Spain and the Holy Roman Emperor all claimed “jus exclusivae” (”the right to exclude”), i.e., the right to veto selection of unacceptably bad man as pope.
The French Revolution (1789) kicked off a 130-year process (culminating with the end of World War I) that terminated, for practical purposes, the temporal power of European monarchs. The Church was a bystander and an opponent of the forces that destroyed monarchy in Europe, i.e. the Pope himself lost temporal power over the areas around Rome with the unification of Italy in 1870, but oddly enough the papacy was a beneficiary of the political transformation. With all the European monarchs deposed or defanged, a vacuum was created and all power over the Catholic Church was gradually consolidated in the papacy ~1870-1919. Around the time of the First Vatican Council (1868-1870) at which the concept of “papal infallibility” was articulated, some Catholics warned of the danger of giving the pope too much power over the Church (e.g., Lord Acton’s famous ‘power corrupts & absolute power corrupts absolutely’ was in reference to the changes happening to the papacy).
So the papacy became more powerful in the 19th century, but for whatever reasons, for approximately a century and a half, divine providence appeared to save the Church from the catastrophe of a bad pope using the office to destroy the Church. And then Bergoglio happened in 2013, and all bets are off.