Obviously most Muslims aren't mass murderers. However, their system of faith in combination with many developing/third-world cultures does lead itself to become more radicalized and violent. You only have to take a quick glance at federal and international terror reports to see that the huge, overwhelming majority of terror attacks (of which there are many across the globe) are performed by Sunni Muslims.

 

Combine that with realtorpat's question of whether they will benefit the nation. Most simply will not and they will find themselves on the dole like the majority of Somalian's in Minnesota. In the end, the risk of bringing them in outweighs the reward.

---