Societies that do believe in this do not have capital punishment. It seems to me from the outside that US have different priorities. Like with school-shootings - apparently that is worth it there.
I mean, Thomas Jefferson said it was self-evident that every man was created equal and had the right to life, liberty and the pursuit of happiness, yet he kept people as property in slavery. That just about sums up American theory vs practice. Same with the legal system: plenty of innocent people have been executed despite it being pretty clear they were innocent, simply because the legal system didn't allow the case to be reopened to handle the new evidence.
No, I don't think supporting "eventual" emancipation is good enough if you don't do anything to actually bring it about.
What a ridiculous reason in hindsight, huh? "Yes, the inevitable reconciliation of our gross injustices against fellow man will be fixed one day. But not now, because I like the comfort of the status quo and would prefer white people not die for a principled cause."
To say nothing of his own slaves, this fickleness of leadership is not what American politics should aspire to.