Prohibiting Muslims from entering the United States sends the wrong message; the West hates Islam. ISIS and other Islamic extremist groups will use that as propaganda. When it comes to combating ISIS, Arab nations are on the front lines. We need them. Suicide attacks are shown on the media much more often than mainstream Muslims, which is why Islam is misinterpreted as a violent religion.
So what if one in five Muslims says the US deserves all the terrorism it gets? They can go hold rallies along side the KKK and fit right into the mainstream with all the other fundamentalists, vote republican and support the NRA, while calling the government and mass media just like any other good conservative.