Religious discrimination is valuing a person or group lower because of their religion, or treating someone differently because of what they do or don't believe. While many religious and secular authorities nowadays tend to stress that religion is something personal, the highly social nature of most religions makes conflicts between religious groups, and thus discrimination, still very probable.
In societies before about 1800, religious discrimination was very standard. More 'enlightened' governments, like the Arab state during its age of expansion, or the Dutch Republic in the 17th century would not persecute religious minorities , but would still officially exclude members of those minorities from public office.
Also see:
Civil rights
Holocaust
Religion
