Locked in on a certain position?

Temporarily take the opposing viewpoint and come up with every possible counterargument imaginable.

Pick it apart. Take every angle you can think of to disprove what you think. You owe it to yourself to develop these counterpoints, as they’ll either disprove your original stance, or help you solidify it. Either outcome is acceptable. In the former case, you evolve your viewpoint. In the latter, you have a coherent and competent rebuttal if the position ever comes up in discussion.

Saying you believe something and then immediately relying on anger to defend it is unacceptable.

Develop a full case for your position so you can defend it properly – and respectfully.