Mere belief is not evidence and evidence is not mere belief
People I talk to routinely confuse the right to speak and believe with the job of being taken seriously. Yes, you can say or believe whatever you want, but that doesn't make it true or even defensible. That takes work. It takes evidence, it takes logical consistency. It requires you to offer some proof of your assertion, not just your testimony, or objections about someone else's assertion.
No. If you want to challenge a theory that explains the evidence, you have to come up with a better, more comprehensive theory that is backed by evidence explains the data more completely and that makes predictions that can be tested in the real world.
And I would add, pushing back on an assertion you make that I think is fallacious is not trampling on your freedom of speech, it's merely asking you back up what you say. In a court of law, you wouldn't accept a testimony against you that was merely someone's opinion. I'm doing nothing different. I'm sorry, but it's not acceptable to merely say, "Well, that's what I believe, and that's good enough."
And finally, evidentiary proof and reason are not simply an alternative, unsubstantiated belief that can be dismissed as merely individual opinion. The physical, natural world is the same for both of us. As the science fiction author Philip K. Dick put it, "Reality is that which, when you stop believing in it, doesn't go away."