RICHMOND, Va. — Ken Cuccinelli learned last week that it’s foolhardy to invoke slavery to make a political point.

The presumptive Republican gubernatorial nominee set off a furor when Democratic Party video surfaced of him comparing the 19th century abolition struggle that triggered the nation’s deadliest war with today’s anti-abortion movement.

In remarks made in June 2012 to a Family Foundation gathering of Christian conservatives in Williamsburg, Cuccinelli connected the dots between the role of churches in the early 19th century played in fomenting the movement to contain and eradicate slavery to that of evangelicals in today’s moral crusade against abortion....