The countries to which the bans apply are all majority Muslim, so the exemption would apply to non-Muslims.
"Trump's Refugee Plan Will Prioritize Christians Suffering Religious Persecution"
The precise wording of the order/legislation may not mention any specific religion, but the intent is clear. Specific countries will be targeted, and exceptions within those countries will be granted, to ensure that Muslims aren't able to get in but Christians can sail right through.
Sadly this leads to some surreal events such as this: http://www.dailymail.co.uk/news/article-3422000/Just-old-thi...
These were common during the inquisition to test convert Jews.
Anusim are Jews who were coerced to convert: https://en.wikipedia.org/wiki/Anusim
All in all there isn't much need to do a bacon test for either Muslims or Jews, at least for men, just make them strip if they are circumcised you know exactly who they are.
Looks like it works, but you simply force people to lie - be that via false confessions or going against halal/kosher practice.
There's various ideologies of that, and some of that are aggressive (repressive) towards the others, which is exactly what is leading to refugee problems in Europe. Is the law going to paper over that difference?
I actually just tried to find out what the attitude towards jewish refugees was in the US and happened upon this eerily pertinent passage:
Out of fear that the Nazis could smuggle spies and
saboteurs in with refugees, immigration officials
tightened visa policies for immigrants and non-
immigrants. The State Department urged its diplomatic
consuls in Europe to screen potential immigrants
carefully, including those fleeing persecution,
(from https://www.ushmm.org/wlc/en/article.php?ModuleId=10007094)