The mark of Cain wasn’t a curse: it was a blessing. God used it to protect Cain: “The LORD put a mark on Cain to warn anyone who might try to kill him” (Genesis 4:15).
In years past, some Christians argued that this mark was black skin and that enslaved people of African heritage were simply living out their destiny as Cain’s descendants. In fact, God put a curse on one man in Cain’s family tree – Ham – whose descendants included people of Africa.
The curse reads, “May they be the lowest of servants” (Genesis 9:25). But the curse was directed at Ham’s son, Canaan, and it was fulfilled when the Israelites took over their land of Canaan.
The Bible doesn’t say what the mark of Cain was, other than it was a mark of mercy.