They are mostly based on ignorance.
Some prejudices are innocent, but others are vicious.
They can lead to oppression and persecution. Few groups in history have encountered more prejudice than the Jews. In Europe, the hatred of Jews has its origins in Christianity, a religion rooted in Judaism. For centuries, the Jews were the only religious minority in Christian Europe, often misunderstood and eyed with suspicion by the population, suppressed by the Church and exploited by the rulers. Religious intolerance led to discrimination and isolation.