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.

At one congressional hearing, Bishop Francis Kalabat complained that administration officials are overlooking what's happening to his fellow Chaldean Christians.

The letter writers span the spectrum from left to right. Members say they don't want this to become a partisan political issue. In fact, there are reasons administration officials have been cautious in making a genocide declaration.

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.

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.

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.

They don't want to feed an ISIS narrative that there is a religious war between Islam and the Christian West, plus genocide is carefully defined under international law.