What is the relationship between the underlined sentence and the bolded sentences?

In any nonviolent campaign there are four basic steps: (1) Collection of the facts to determine whether injustices are alive; (2) Negotiation; (3) Self-purification; and (4) Direct action. We have gone through all of these steps in Birmingham. There can be no gainsaying of the fact that racial injustice engulfs this community. Birmingham is probably the most thoroughly segregated city in the United States. Its ugly record of police brutality is known in every section of this country. Its unjust treatment of Negroes in the courts is a notorious reality. There have been more unsolved bombings of Negro homes and churches in Birmingham than any city in this nation. These are the hard, brutal, and unbelievable facts. On the basis of these conditions Negro leaders sought to negotiate with the city fathers. But the political leaders consistently refused to engage in good faith negotiation.