All-Star Comics #22

After witnessing an attack on a boy because of his religious beliefs, Dr. Mid-Nite takes the young victim to the JSA, and lets the boy tell his story. But the members aren't sure how they can help until suddenly a strange female being appears and tells them they can IF they are willing to undergo a test, which they agree to do. Each member will be hurled back in time to eras of great persecution and prejudice [without their present knowledge] to become opponents of those prejudices and hatreds. If they let the difficulties of the past overcome them, they will fail their missions.