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.

Fidel Castro was not interested in personal enrichment. His supporters say he deployed his enormous authority on behalf of health, education and welfare programs that brought Cuba attention around the world.

A similar move is underway in the British Parliament. Earlier this month, more than 30 religious leaders and scholars wrote Secretary of State John Kerry asking for a meeting to discuss what's happening to Christians and other minorities. Nina Shea organized the effort.

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.

In some states, it is illegal to turn down a same-sex couple when you're placing children for adoption. That's discrimination. But in the Catholic church, the sacrament of marriage is defined officially as the union of a man and a woman. So a Catholic adoption agency is torn between its faith doctrine and what it sees as a faith obligation to help orphans.

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

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.