It is my guess that ignorance is the reason that many people do not like the Confederate flag. Most of the people who hate this flag don't even know that it is the Confederate Naval Jack flag. It was displayed by Confederate ships.
The Confederate battle flag carried by soldiers on land was square not rectangular.
As it has been said... not a single slave ever came to the US from Africa on a ship flying the Confederate flag. They came on US ships flying the US flag and also they came on European ships.
Also as already noted here...
The US had slavery for 90 years.
If you go back to when we were British colonies, we had slavery here for over 200 years.
The Confederacy only had slavery for 4 years.
Most of the people who have issues with the Confederate flag need a history lesson.
By the way here is the Confederate flag...No one seems offended by this flag.
