The best way to fight ideological tyranny is with the truth, and since ideological tyranny is propagated by those who hold power (government, media, Big Tech, etc.), the only way for truth to out is for censorship to never, ever be tolerated. It is the first and most critical step toward totalitarianism.

As Milton Mayer writes in They Thought They Were Free: The Germans, 1933–45:

“Free inquiry on a free platform is the only practice that distinguishes a free from a slave society.”

See more harrowingly applicable quotes from the book recommendation section of this piece: