The Christians would have dug their own passages and burial chambers centuries later.
6 seconds sound clip from the Indiana Jones and the Last Crusade movie soundboard.
You can hear this line at 00:30:54 in the Blu-ray version of the movie.
Quote context
[...]
- Except he's lost, and I'm not.
- Look after this for me, will you?
- Come on.
- Pagan symbols. Fourth or fifth century.
- Right. 600 years before the Crusades.
- The Christians would have dug their own passages and burial chambers centuries later.
- That's right. If there's a knight of the First Crusade down here, that's where we'll find him.
- It's petroleum. I should sink a well down here and retire.
[...]