Abraham Lincoln believed that slavery was unjust and that no human should be sold like cattle. He did not believe though that the African slaves and their descendants could co-exist with the rest of society. That is why he supported the idea of shipping slaves to Liberia.
African American abolitionists felt that Abraham Lincoln moved too slow in ending slavery and guaranteeing civil rights to slaves. Federick Douglas, for one, did not like Lincoln from the outset but that gradually changed when he met him in the White House and came to believe him to be a political genius. Lincoln could not say that part of the reason why the North waged the Civil War was for to abolish slavery for fear of losing the Border States and the support of his Northern constitutencies