Jeremiah 13:23 KJV Even in the bible refers to black as being evil
(media.scored.co)
Nah, its more saying that changing your skin color is as difficult as it is to repent without the Grace of God. The people referred to as "Ethiopians" in the bible also vary do to ethnic groups moving around. Sometimes its referring to the negro empire, but other times it actually refers to Arabia and Arabs, for instance when Moses' wife is called an "Ethiopian", its referring to her being an Arab (and therefore of the same racial group as Moses, more akin to Frenchman marrying a German woman) and not a black from Ethiopia.