ISIS goes after any group that deviates from its extreme ideology, dissident Muslims, for example, or the Yazidis who practice an ancient religion distinct from both Islam and Christianity.

The country has already become multicultural. Given immigration trends, it will only grow more diverse, and these new Americans want to share in their country's identity.

One of Donald Trump's criticisms of President Barack Obama and of Hillary Clinton was that they seemed reluctant to use the words radical Islam. It was not just semantics. Trump said it's important to name the enemy idea and then attack it. Consider the Cold War. The U.S. and its allies waged a kind of propaganda war against the communist idea using radio broadcasts and other tools. Trump has said he'd do the same against Islamic extremism.

Muslim immigrants like himself encounter prejudice here [in U.S.] but also find political and religious freedom.

When ISIS last year called for the destruction of the Yazidi people, President Obama said that would constitute genocide and he ordered U.S. forces to keep it from happening. Human rights advocates say Christians now face a similar threat Nina Shea directs the Center for Religious Freedom at the Hudson Institute.

Trump has always talked about how important in dealing with foreign leaders, how important it is to establish a good personal relationship very close to what Pope Francis says, so they may both really want to emphasize their development of a personal relationship.

The First Amendment to the Constitution says government can't establish a religion, but neither can it limit the exercise of religion. And that's the issue here. What does it mean to be free to exercise your religion? It's not about what you can believe. It's whether you can act on those beliefs.