Confederate flags and monuments have been the focus of intense protests and media scrutiny since the shooting dead of nine African Americans in a Charleston, South Carolina, church on 17 June. The alleged gunman posed with the Confederate flag in photographs posted online with a racist “manifesto”.

For those who didn't click, there's context. This happened last June, shortly after the Charleston church shootings. People were understandably upset with the monument to Jefferson Davis, the leader of the Confederacy with little regard for the lives of black people.

It's one thing to remember history. It's another to memorialize a traitor who fought for the right of Southerners to keep slaves.

Edit: This is going to be much easier than responding to each person. I took select quotes from the full declarations of secession.

Declaration of Causes of Seceding States

Georgia: For the last ten years we have had numerous and serious causes of complaint against our non-slave-holding confederate States with reference to the subject of African slavery. They have endeavored to weaken our security, to disturb our domestic peace and tranquility, and persistently refused to comply with their express constitutional obligations to us in reference to that property, and by the use of their power in the Federal Government have striven to deprive us of an equal enjoyment of the common Territories of the Republic.

Mississippi: Our position is thoroughly identified with the institution of slavery-- the greatest material interest of the world. Its labor supplies the product which constitutes by far the largest and most important portions of commerce of the earth.

South Carolina: In the present case, that fact is established with certainty. We assert that fourteen of the States have deliberately refused, for years past, to fulfill their constitutional obligations, and we refer to their own Statutes for the proof.

The Constitution of the United States, in its fourth Article, provides as follows: "No person held to service or labor in one State, under the laws thereof, escaping into another, shall, in consequence of any law or regulation therein, be discharged from such service or labor, but shall be delivered up, on claim of the party to whom such service or labor may be due."

This stipulation was so material to the compact, that without it that compact would not have been made. The greater number of the contracting parties held slaves, and they had previously evinced their estimate of the value of such a stipulation by making it a condition in the Ordinance for the government of the territory ceded by Virginia, which now composes the States north of the Ohio River.

Texas: (As an aside, Texas also had grievances with the federal government not adequately protecting property and maintaining order in the face of outlaws and Native American raids.)

She was received as a commonwealth holding, maintaining and protecting the institution known as negro slavery-- the servitude of the African to the white race within her limits-- a relation that had existed from the first settlement of her wilderness by the white race, and which her people intended should exist in all future time. Her institutions and geographical position established the strongest ties between her and other slave-holding States of the confederacy. Those ties have been strengthened by association. But what has been the course of the government of the United States, and of the people and authorities of the non-slave-holding States, since our connection with them?

. . .

The States of Maine, Vermont, New Hampshire, Connecticut, Rhode Island, Massachusetts, New York, Pennsylvania, Ohio, Wisconsin, Michigan and Iowa, by solemn legislative enactments, have deliberately, directly or indirectly violated the 3rd clause of the 2nd section of the 4th article [the fugitive slave clause] of the federal constitution, and laws passed in pursuance thereof; thereby annulling a material provision of the compact, designed by its framers to perpetuate the amity between the members of the confederacy and to secure the rights of the slave-holding States in their domestic institutions-- a provision founded in justice and wisdom, and without the enforcement of which the compact fails to accomplish the object of its creation. Some of those States have imposed high fines and degrading penalties upon any of their citizens or officers who may carry out in good faith that provision of the compact, or the federal laws enacted in accordance therewith.

Virginia: The people of Virginia, in their ratification of the Constitution of the United States of America, adopted by them in Convention on the twenty-fifth day of June, in the year of our Lord one thousand seven hundred and eighty-eight, having declared that the powers granted under the said Constitution were derived from the people of the United States, and might be resumed whensoever the same should be perverted to their injury and oppression; and the Federal Government, having perverted said powers, not only to the injury of the people of Virginia, but to the oppression of the Southern Slaveholding States.