What was John Milton Church fighting against when, in 1644, he advocated strongly for a diversity of voices and a marketplace of ideas?

censorship

Explanation:

John Milton was one of the most influential intellectuals of England in the seventeenth century but what gained him universal fame was his writing in English, Greek, Latin and Italian. In response "The Doctrine and Discipline of Divorce" which was published without the license, he wrote "Areopagitica" which was the most influential defense of freedom of press. His stand for the anti-censorship reflects his belief in freedom of speech.