"The Spanish answer to that in the 1400s was the Spanish Inquisition."
1. I wasn't expecting the Spanish Inquisition.
2. On a more serious note...do we REALLY want to run things in the way that Spain did in 1400?
It's hard to argue with success. The Muslims left and they had almost 600 years of peace from Jihad.
It wasn't as bad as popularly assumed, especially considering the fact that they had just spent 500 years driving the Mohammedans out of Spain.
The Myth of the Spanish Inquisition
The best policy for containing Mohammedanism is to stop Mohammedan immigration, introduce democratic institutions to Mohammedan lands (this is actually antithetical to Mohammedanism), and to promote institutional change in Mohammedan lands that will improve their living standards, allowing them private access to non-Mohammedan religious reading material.
Mohammedans are notoriously difficult to convert, probably because of their general ignorance and the militancy of their diabolical religion.