What assumption do the clergymen rest their arguement upon

The most prestigious clergy in the state of Alabama all racial moderates, who had condemned the protests roiling that city of fierce racism and branded Martin Luther King an extremist.

Explanation:

Martin Luther King's main aim in sending his letter from a Birmingham jail to clergymen was to speak about the condemnation directed against him by individuals who unarguably should have known better. The knowledge and preaching of Jesus, he constantly, provided for the nonviolent activities that were only intended to correct injustices.

The letter says that people have an ethical accountability to break unfair laws and to take straight action rather than waiting for justice to come through the courts. Further, he argues that white moderate people are putting obstacles for equality for black people.