In the movie Gerard Thom explains that these parchments were preserved by the priests to pass on a huge secret - the secret of the Rennes-le-Chateau region and the Cathars, and also the secret of the church. Thom explains further that the secret is that Jesus did not die on the cross but was smuggled out of Jerusalem and along with Mary Magdalene and their children, were brought to France.
Bruce Burgess explains that on the face of it they are passages from the bible, but Thom said that by using a small cipher on one of the parchments, a secret text appears.
An example of Thom's deciphered code
When asked about the authenticity of the parchments and the messages they contain, Thom answers "The papers are indisputable."
Thom tells Bruce the oldest parchment dates from the French Revolution. (It began in 1789)
Also some of the parchments are symbolic maps that will lead to the tomb of Mary Magdalene and Jesus Christ. Then pointing to the parchments Thom says, "If one believes what the priests have said, the bodies are still in a mummified state."
Bruce sums up the meeting with Gerard Tomb by saying the parchments reveal that the embalmed bodies of Jesus, Mary Magdalene and their children lie in an underground Temple somewhere near Rennes-le-Chateau.
Thom than adds, "The Temple is a reconstruction of the Temple of Solomon built in the fifth century before Christ."