This refers to either marrying close relatives (forbidden in most cultures) or marriage between those of different races or religions. Cultural and social differences between vastly different ethnic groups can result in dissimilar expectations. These can present major conflicts inside the marriage, as can partners holding to different religions. While we are to be friendly with non-Christians and those of different nationalities and religions, the Bible says a believer should not marry an unbeliever (2 Cor 6:14). Compatibility in a marriage partner is more desirable than the novelty of a person with completely different values, customs and views.