Just so you know: The government already has a list of Muslims in the U.S. - The Washington Post

A topic apparently not included in Donald Trump briefings

"The brokers learn who you are "by amalgamating data from people's offline lives and their online lives," he said. Data such as credit card purchases, browser history, online shopping, who you donate to, magazine and newspaper subscriptions, purchases in grocery stores where you swipe your loyalty card. Particularly for credit card purchases, "it's really trivially easy for that data to be sifted and sorted," Sparapani said. All of that data isn't always specific to an individual (whose Time magazine subscription is it, anyway?), but data can also easily build out a profile of a household. Where you vacation. Where you work. They can analyze languages spoken and last names to develop a picture of a person's or family's ethnicity, or religion. It goes on. 

Where does this overlap with the government? The government could create a tool to pull in data from all of these other places, too. But why bother, when the private sector already has? "I think it's a well-established fact that the government, writ large, is the largest source of funds for the data brokerage industry," Sparapani said. "They have elastic budgets. They can spend whatever they think they need to spend, particularly post-9/11 and in an era of ISIS commanding our attention." Many of those budgets are classified."

Just so you know: The government already has a list of Muslims in the U.S. - The Washington Post