You are incorrect in your statement mr. Tractor, not all those documents stated that whites are superior.  They did list slavery to one degree or another as a partial reason for SECESSION,  but secession is not war.  The Confederate battle flag in question did NOT even exist at the time those documents were written.  It should also be noted that you list only 4 out of 13 secession declaration documents.  None of the others list slavery as even a partial reason.  
Please note that Stephens was against secession but his state seceded anyway. Also note that Lincoln held similar racist views and that not all or even most southern leaders agreed with Stephens. 
Even if you try to make a case that secession was caused partially over slavery that does not affect the battle flag nor the causes of the actual war, which is separate from secession. 
Lincoln stated the war was over taxes and revenue,  not slavery.  
The war was not over slavery,  the battle flag is not about slavery.