If it is not in the current immigration law it should be. ANY immigrant that is caught or involved in any anti American activity should be arrested and immediately deported to whereever they came from. No ifs ands or buts.
When I was a kid in grade school, every morning we all fell out on the parade ground and had to say the pledge of allegience. Any one refusing to do so should be at least looked at as a potential risk to the country.
Any one that cannot accept the "Freedom of Religion" and "Freedom of Speech" should be denied access to the cvountry.