"At the Cooper Union, Lincoln noted that these threats were always accompanied by casting of blame on anti-slavery men.
But you will not abide the election of a Republican president! In that supposed event, you say, you will destroy the Union; and then, you say, the great crime of having destroyed it will be upon us! That is cool. A highwayman holds a pistol to my ear, and mutters through his teeth, "Stand and deliver, or I shall kill you, and then you will be a murderer!"What is just as 'cool' (in Lincoln's usage) is the argument used by Southern apologists today against him: Lincoln moderated his positions on slavery to avoid provoking Southern fanatics, therefore he should be condemned more than them!"
Walt
He did not simply moderate his views - he catered them to whatever audience he was speaking to at that given moment and political circumstance. Lincoln was all over the radar on slavery. His views run the gamut from permanently enshrining it in the constitution to permanently banning it along with practically everything in between. No other characterization of them is historically supportable.