The Swiss can do what they like in Switzerland. It’s their country. May I propose another question?
Can America ban islam ... or the construction of mosques ... or the erection of minarets ... and still be America?
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Yes.
Islam is treason, which competes with the Constitution.
How so?
Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court. The Congress shall have Power to declare the Punishment of Treason, but no Attainder of Treason shall work Corruption of Blood, or Forfeiture except during the Life of the Person attainted.
Simple assertion will not do. Treason, in these United States, is defined above. Please elaborate on how adhering to islam (or any other religion) is treason.