Simple. If they believe the Koran is superior to the US constitution, they do not deserve to live here under the US constitution, and should be encouraged to go live in a place under the dictatorship of the Koran and Sharia law.
If they do not want to do so, for fear of being tortured and murdered, it is because they think that the Koran and Sharia law are *inferior* to the US constitution. So, in effect, if they refuse to return, they are denouncing Islam.
All Muslims are sworn to overthrow our government. Some are actively killing to do this, some are marching but all Muslims are complicit with that goal.
The goal is to overthrow the US government and enslave EVERYONE under a Sharia Law hell.