When is obedience to a created being considered major shirk (polytheism)?

Obeying a creature becomes major polytheism (shirk akbar) if it leads to legalizing what is forbidden or forbidding what is lawful, or believing that the creature's legislation is more perfect than or equal to Allah's law, as the Christians did with their rabbis. However, if a person obeys their parents in an act of disobedience while knowing it is an act of disobedience, this is not considered major polytheism but rather an act of disobedience and sin, because "there is no obedience to a creature in disobedience to Allah, the Mighty and Majestic." A Muslim must prioritize obedience to Allah and His Messenger above all other obedience, and Allah and His Messenger must be more beloved to him than anyone else.