The lyrics to "Viva la Vida" contain many religious references. For example, "pillars of sand" is a clear reference to the Biblical parable given by Jesus about the fool who built his house on sand, and the wise man who built it on solid rock, while "pillars of salt" is a reference to Lot's wife, who was turned into a pillar of salt. "I know Saint Peter won't call my name" refers to the popular mythos of St. Peter guarding the gates of Heaven; he is often depicted in art and cartoons as holding the book of life and reading off the names of those souls found worthy to enter the Kingdom of Heaven. Other likely (but ambiguous) references are "Seas would rise when I gave the word" (King Canute allegedly gave an order for the seas to rise, in order to prove to his subjects that he was not all powerful), and "... my head upon a silver plate" (the beheading of St. John the Baptist: Salome asked to have his head delivered to her upon a platter). Also, "I hear Jerusalem Bells a ringing, Roman Calvalry choirs a singing," Romans were the ones who were persecuting Jesus because they were feeling threated (power wise). So if the Romans were singing, that would refer to the crucifixion of Jesus.

The song has inspired a great deal of debate about its meaning. People have claimed that the song may be about various subjects, such as the French Revolution. The band members themselves do not appear to have corroborated any of these claims, and have referred only to kings and revolutionaries in general, rather than any particular king.

Martin has explained the song lyric "I know Saint Peter won't call my name" in an interview with Q magazine: "It's about ... You're not on the list. I was a naughty boy. It's always fascinated me that idea of finishing your life and then being analyzed on it. And this idea runs throughout most religions. That's why people blow up buildings. Because they think they're going to get lots of virgins. I always feel like saying, just join a band ... That is the most frightening thing you could possibly say to somebody. Eternal damnation. I know about this stuff because I studied it. I was into it all. I know it. It's still mildly terrifying to me. And this is serious." When asked about the song, bass guitarist Guy Berryman said: "It's a story about a king who's lost his kingdom, and all the album's artwork is based on the idea of revolutionaries and guerrillas. There's this slightly anti-authoritarian viewpoint that's crept into some of the lyrics and it's some of the pay-off between being surrounded by governments on one side, but also we're human beings with emotions and we're all going to die and the stupidity of what we have to put up with every day. Hence the album title."

Unlike the typical arrangement of Coldplay songs, in which either the piano or guitar is the prominent instrument, the track mostly consists of a string section playing the song's upbeat riff, along with a steady bass drum beat, percussion (including a timpani and a church bell), bass guitar, and Martin's vocals; there is limited use of electric guitar in the song. All the strings are arranged and performed by violinist Davide Rossi, who is also one of the main collaborators of the album. Rossi's strings comprise the main driving force throughout the song, with a strong beginning loop that supports Martin's voice, until the choruses where the symphonic power of the orchestra takes its fullest shape. The song is played in the key of Ab Major at a tempo of 137bpm, while the vocal range is Eb4-Ab5. Although Coldplay are widely labeled as an "alternative rock" band, the classical composition and historical subject matter of "Viva la Vida" have led to the song being labeled as "baroque pop" and "chamber pop".