The Poem of the Cid is a fabulous picture of life and politics of the Spanish Reconquista. The poem's discussions amongst the Spanish Christians and both Moors and Jews exemplify the attitudes of most people of that age.
There is little sympathy for the Jews of the poem. It is Jews who provide cash for the Cid's exile--in exchange for boxes of sand. They are painted as usurous fools.
The Moors, on the other hand, seem to be able to earn the respect and friendship of the Cid (and others.) The Cid fought to reclaim Spanish land from the Moors, and he successfully fought against two different Moorish kings (cutting one of them vertically in two!) However, the Cid also has Moorish allies, most notably Abengalbon.
Interestingly, it is Christians who are both hero and villain in the poem. The Infantes de Carrion are part of a corrupt nobility, while El Cid is from a lower place in society, yet has integrity, honor, and character. In the end, the "true Christian" triumphs over the unworthy.