I'm not sure if Christians have this belief or not, but Muslims believe that the lifespan of people (and their sizes too) were very different than it is today. For example it is said that Noah died around the age of 1000 (yes, 3 zeros) and Adam lived twice as much and was 22 feet tall (Kinda like reverse evolution lol).
With this in mind they believe that the earth is much, much older than that.
Yeah, that's in the Christian Bible. (I typed Christian Bale at first; I need sleep)
Malice yes, but founded in what they thought was scientifically sound at the time (social darwinism).
Antisemitism was obviously not founded by Social Darwinism: It has thousands of years of history. And 20th century German antisemitism can easily be traced back through the Middle Ages. It has always been based on bigotry and hatred, not on a mistaken theory. Social Darwinism just aided pre-existing prejudices, and probably prejudices in the Anglo world more than Germany.
It's doubtful that Social Darwinism is causing today's antisemitism either. For example, Canada's most well-known antisemite, Jim Keegstra, is a creationist.
Unlike creationism (to a point) which has been proven wrong for a while now.
Until Darwin, creationism was the only game in town, based on the only, simple explanation at the time people could comprehend. It really wasn't displaced until fairly recently.