If you have enough people you can establish a religion that treats a certain binary number (which also happens to represent an arbitrary algorithm) as a sacred text.

The source code would practically be in the transformation, the bible would only be a key.

Right, and that's what is interesting about the OP.

They found a piece of information that is notable in its own right (by being one of the larger primes discovered through a particular algorithm). This single piece of information, without any further interpretation, can executed in order to perform the illegal DeCSS operation. IOW, somebody tells you that it's the Nth largest number proven prime by {mumble], and you copy that number out of the math book into an executable file, run it, and you're a criminal.

Eh, you could deliberately word-substitute and reformat the bible so that it, itself, contains the data in some form.

Only if you could do that by some meaningful and simple process. If you simply generate a table (of the same length as the source code) that produces the source code when added to the bible, that's just basic cryptography, a sort of indirect way to store the source code.

Nah, what I'm proposing is steganography not cryptography. Encode it hidden within the text in terms of word lengths, comma positions, number of commas per sentence, word capitalisation, or some other property like that:

https://en.wikipedia.org/wiki/Steganography

Use Synesthesia to build up a coloured picture of the ilegal prime. Boom "Art".