You're right, human authority is liable to abuse. However, we are called to be obedient to God, either so that He may direct us towards some mission, or so that we may learn humility and grow in virtue. Legitimate authority is not invalidated by abuse of a position of power.

That said, the situation is complex here in the West, because our social order is built on principles of self-government. It takes a lot of prudence to know when to submit in humble obedience to legitimate authority and when to stand up to correct an injustice.

No one is going to get into Heaven by "my way or the high way," though, so we do have to learn obedience and humility in order to attain greater union with God.