Why then should the South believe any statement made by Lincoln?
We know what the State of Georgia thought about the Republican Party: "The prohibition of slavery in the Territories, hostility to it everywhere, the equality of the black and white races, disregard of all constitutional guarantees in its favor, were boldly proclaimed by its leaders and applauded by its followers ... We know their treachery; we know the shallow pretenses under which they daily disregard [the Constitution's] plainest obligations."
They were motivated because they didn't trust the treacherous Republican Party to maintain slavery.
> Why then should the South believe any statement made by Lincoln?
Because it was politically infeasible to actually abolish slavery in the next 4 years and because Lincoln is still accountable to his northern voters (overwhelming majority of whom preferred the continuation of slavery to the collapse of the Union).
> They were motivated because they didn't trust the treacherous Republican Party to maintain slavery.
I'm not sure treachery is the right word. Republicans were generally pretty open their desire to weaken the institution of slavery and limit it's expansion into new territories. Eventually that would've probably led to abolition.
You are rejecting the literal words they used to describe the Republican party, which I quoted. Those are by definition the right words for describing their viewpoints because that is what they wrote.
You also reject the reasons they wrote to justify secession, because you think it did not make sense. Remember, these are people who believed "the servitude of the African race, as existing in these States, is mutually beneficial to both bond and free, and is abundantly authorized and justified by the experience of mankind, and the revealed will of the Almighty", and whose use of slave labor enriched their economy - you have different belief in what God wanted, so cannot use your beliefs as a lens to interpret what made rational sense to them.
You cannot have a good understanding of history if you filter the primary documentation through your own interpretations and discard anything that does not make sense to you.
No, I never said that.
> Remember, these are people who believed "the servitude of the African race, as existing in these States, is mutually beneficial to both bond and free
How is this relevant? I never defended slavery or claimed that the southern states did not rebel to protect slavery.
> if you filter the primary documentation through your own interpretations and discard anything that does not make sense to you.
I'm not doing that either.
Did you read the quote you posted?
> "The prohibition of slavery in the Territories, hostility to it everywhere, the equality of the black and white races, disregard of all constitutional guarantees in its favor, were boldly proclaimed by its leaders and applauded by its followers ... We know their treachery; we know the shallow pretenses under which they daily disregard [the Constitution's] plainest obligations
Could you explain how exactly am I misinterpreting it?
If you reading that quote as "we believe that the abolition of slavery is imminent and will happen in the next years" that's a pretty obvious misinterpretation.
Obviously it was about slavery in the broad sense but the rebellion was mostly preemptive and they had to come up with some justification. Chances are that slavery would've lasted another 10-20 years had the southern states not seceded.