Check out Mozart's "Requiem" and Karl Orff's "Carmina Burana". My personal picks from each work are (from Requiem) are Requiem Aeternam, Rex Tremendae Majestatis, Confutatis Maledictis, Lacrimosa Dies Illa, Agnus Dei and Ave Verum Corpus; (from Carmina) O Fortuna and Omnia Sol Temperat. O Fortuna is popular for its climactic rhythm ergo its use in many movies.
Check out other Religious works too, like the different Ave Marias, Haydn's Te Deum, and the like. For a representative sample check out modern performers, like Andrea Bocelli's "Sacred Arias" and Charlotte Church. "The Prayer", while is a modern composition, is a really good song, and my favourite permance is the one by Bocelli and Dion.
THis may not be a modern "Classical" song by many people's standards, but the vocal work on "Canto Alla Vita" by Josh Groban and The Corrs is, while not as good as Bocelli, is enchanting, something you might want to listen to with a good soundsystem, then sit back and sip some tea.
As for the Classics, Id suggest certain books/essays to go along with those: St. Augustine's "City of God", Rosseau's "The Social Contract", "Emmanuel Kant's "Critique of Pure Reason" and "Perpetual Peace", Nieztche's "Der Wille Zur Macht" and "Genealogy of Morals", Hegel's "Philosophy of Right", Heidegger's "Being and Time".