An app called Bless Every Home, which has been backed by some of the biggest names in evangelical circles, is mapping the names and addresses of immigrants and non-Christians.
I mean they don't need sensitive data, they already know which house is religious, because the people signed up for it.
So by default every other home gets added.
That is all very puplic information.
It says in the article they employed a commercial data set that is not composed of widely available public data in creating this app. Also, it lists a lot more information about people than whether or not they are christians.