When it comes to expressing your disagreement or opposition to something, there are various synonyms that you can use instead of the phrase "protest against". Some of these synonyms are "object to", "oppose", "disapprove of", "rebuke", "condemn", "challenge", "argue against", "reject", "denounce", and "criticize". Each of these words carries a different degree of resistance or disagreement, and it's important to choose the right word based on the context and the intensity of your objection. By using these synonyms, you can add more variety and emphasis to your language, and communicate your thoughts and feelings more effectively.