Silicon Valley Has Already, Accidentally, Created a Muslim Registry
nymag.com
nymag.com
A huge portion of Muslim men are named Mohammad or some derivation thereof. There are notoriously few people called Mohammad who are not Muslim so the false positive rate isn't going to be very high.
If you wanted to start your database you would simply pick up a phonebook.
The article clearly states, the advent of the Internet has created a much more efficient information gathering system. What might appear to be meaningless information collected by private companies can allow software to ^infer^ much more than just a name might indicate. Inference via ^software defined^ characteristics shortens the detail/arrest lists in the same way intelligence software shortens the kill-chain for the military.