Most basically, paganism is the worship of nature as self-generating and divine; one consistent characteristic is focus on reverence for the creation in contrast to worship of God (cf. Rom. 1:25). Theistic religions, such as Judaism and Christianity, view God as simultaneously transcendent (above and beyond the created order) and immanent (present and available to his creation). Christianity views God as the Divine Creator, and everything else as his creation; paganism predominantly sees "god" as being within-within humanity and within creation itself.

Early in The Da Vinci Code (7), Robert Langdon has just delivered a lecture about hidden pagan symbols in the stonework of Chartres Cathedral (about fifty miles outside of Paris). Construction began in 1194, but wasn't completed until 1220, and the cathedral was finally dedicated in 1260. It's one of France's grandest examples of Gothic architecture characterized by magnificent ornamentation, imposing figures, memorials to royalty and saints, and local legends.

Since many symbols have wide appeal and broad meanings, symbols on such an ornate structure could be reinterpreted by a creative imagination to have pagan connections. However, the novel doesn't say what these pagan symbols are, leaving the assertion undemonstrated and unproven.