In the essay "What is Enlightenment?" (or "Answering the Question: What is Enlightenment?"), Kant says that enlightenment is "man's emergence from his self-imposed nonage." This means that enlightenment is a man/woman progressing from a state of self-imposed naivete to a state of autonomous reason. One must have courage to leave behind the naive (nonage - immature or infantile) state to embrace the self-reliant state of an enlightened individual.
An enlightened person has ceased letting others think for him and takes on that responsibility himself. In addition to having courage, one must have the freedom necessary to use reason in all aspects (private and public, individual and social) of one's life. The more free a whole society is, the more enlightened that society can become.
Enlightenment is not a utopian end but an ongoing process. Therefore an enlightened society should continue to endorse the freedom to question current institutions and knowledge in order to continue to progress.
But, while this provisional order continues, each citizen (above all, each pastor acting as a scholar) should be left free to publish his criticisms of the faults of existing institutions.
In an enlightened society, a ruler or authority who is enlightened will recognize the benefits of encouraging free thought; "he knows that there is no danger in permitting his subjects to make public use of their reason and to publish their ideas concerning a better constitution, as well as candid criticism of existing basic laws."