A major difference between the CSA and the USA is that the CSA was formed for the perpetuation of slavery. That's it. The USA was formed for freedom from tyranny. Yes, many people owned slaves when the USA was formed, including the first president and some of the writers of the Constitution and Declaration. However, as Lincoln, and even more significant, Frederick Douglass, pointed out, the Declaration contained the seeds of freedom that helped fuel the abolition of slavery. Douglass appealed to assertions of natural rights and freedoms in the Declaration as the basis (along with God and reason) to end slavery. He called for those rights to apply to everyone and not just white citizens. I suggest that everyone read Douglass's Independence Day speech given in 1852 -- thirteen years before slavery was finally banned.
http://www.historyisaweapon.com/defcon1/douglassjuly4.html

To respond to your statements, specifically:
1. I never said or acted like the CSA was the only country to have slavery. Slavery has existed all over the world for thousands of years. Those other countries that had slavery, however, have nothing to do with any Confederate flag. Even the designer of the flag, William T. Thompson, called it "the white man's flag." The battle flag actually became the basis for the SECOND official CSA flag in 1863.
2. As I wrote earlier, what Lincoln said isn't relevant since the Southern slave states started leaving the Union BEFORE he was sworn in as President AND the CSA was formed for the perpetuation of slavery. The USA was not formed for the perpetuation of slavery. In fact, there are items in the Constitution that put limits on slavery, such as the ban on importing slaves in 1808 and the 3/5 of a person clause (it wasn't to deny the personhood of black slaves, it was because the Southern states wanted their black slaves to count for purposes of representation while they denied them the right to vote, the opponents said that if they couldn't vote then why should they count as citizens? The result was a compromise).
3. Well, some people are going after the Stars and Bars. The difference is, however, that the USA realized its wrong and tried to fix the problem, but the CSA didn't think that the problem of slavery was wrong or a problem and formed because it liked anti-black racism and slavery.
4. Okay, we'll ignore the KKK and AB for this point. I will agree with you that many white people and some black people don't see racism in the flag. However, go along with me on this one...try to look at it from the point of view who only saw the bad side of the flag.

First, remember that the flag was created by CSA people and the CSA, like it or not, only existed to keep slavery and racism going. After the Civil War, veterans of the CSA started using the battle flag in their get-togethers. (I know that most CSA soldiers did NOT own slaves, but they still fought for a government that existed because of racism and slavery.)

Second, remember that the CSA battle flag was used by the Dixiecrats in 1948. The Dixiecrats wanted the continuation of racist Jim Crow laws and if they didn't support lynching, couldn't care less when it happened. Remember too, there are plenty of people still alive today who were alive in 1948. They're old, but they shared their stories with their children and grandchildren.

Third, remember that Georgia and Mississippi changed their state flags to include the CSA battle flag after the 1954 school integration ruling (Brown v Board of Education). For them, the battle flag was a protest against integration. They wanted to keep black children in poor, inferior schools. There are even more people alive today who were there when those states changed their flags in 1956. So the flag represented a continuation of Jim Crow laws in the South.

Fourth, most Jim Crow laws were only officially ended in 1964 with the second Civil Rights Act. I was a year old when it passed, so there are plenty of people still around who remember Jim Crow laws. Less than a month before I was born, Birmingham, Alabama mayor Theophilus Eugene "Bull" Connor ordered police to use firehoses and dogs to attack CHILDREN who were peacefully protesting Jim Crow laws. Prior to this, Connor closed down all public parks rather than integrate them. The attack on the children was televised all over the country and it made viewers see with their own eyes the brutality of Jim Crow. It was so bad that even the citizens of Birmingham voted Bull Connor out of office less than two weeks later. Even then, the last Jim Crow-style law, against interracial marriage, was not struck down until 1967.

Fifth, I know I said I would leave out the KKK, but it's relevant here. In the 1950s and 1960s the KKK was active in the South and KILLED PEOPLE. They weren't just a bunch of nutjobs, but were dangerous. And yes, the flag was associated with them too. Recall I what I wrote about the Jim Crow laws being overturned in 1964 and 1967. Separate from that, white attitudes didn't change overnight. Anti-black racism was still dominant and the KKK at that time included police officers, lawyers, judges and mayors. Today it may be limited to a bunch of losers, but back then it had people with power. That's why when people were lynched, like Emmett Till, nobody was prosecuted. I urge you to read up on Jim Crow and how it controlled all aspects of black life in the South.

The point of all this: try to put yourself in the shoes of those who do see it as a symbol of slavery and racism. Try to imagine their experiences. After you do that, see if those who are against the flag are just a bunch of left-wingers with an agenda. Don't forget that the previous conservative Republican governor of South Carolina, David Beasley called for removing the flag in 1998. He wasn't re-elected.