Silas's planning on using a heavy iron votive holder to smash open the marble tile. That should be pretty noisy.
He uses his cloak to muffle his improvised battering ram, leaving him naked except for his loin swaddle (two words we'd hoped we'd never have to put together…)
He successfully breaks the marble tile, and reaches in to the hidden compartment, retrieving an engraved stone tablet.
The inscription reads: "Job 38:11," a bible verse.
Sister Sandrine's watching all of this from above. She's horrified at Silas's actions, and that she's actually being called upon to act in a situation that they'd always hoped would remain hypothetical.
She rushes back to her room to dial four Paris phone numbers.
Uh-oh. Silas looked up the bible verse at the church altar. He's pretty confused. It reads: "Hitherto shalt thou come, but no further."