President Obama raised an often overlooked element of international diplomacy last week in an appropriate forum. At the National Prayer Breakfast, he declared that promoting religious freedom around the world is a bulwark of U.S. foreign policy.

Mr. Obama further heartened advocates of religious freedom when he called on China to accommodate Christian worship, demanded that North Korea release a Christian missionary it has held for 15 months and that Iran release a Christian pastor it has held for 18 months.

"History shows that nations that uphold the rights of their people, including the freedom of religion, are ultimately more just and more peaceful and more successful," Mr. Obama said. "Nations that do not uphold these rights sow the bitter seeds of instability and violence and extremism. So freedom of religion matters to our national security."

All of that is demonstrably true. It's akin to the maxim that capitalist countries rarely go to war against one another. The saying is that countries that host McDonald's don't fight. Much the same is true of countries that embrace religious tolerance at home and abroad.

Yet the president, like several of his predecessors, has not attended to the diplomatic infrastructure by which the United States more effectively could promote religious freedom. He did not nominate an ambassador at large for religious freedom until the summer of 2010, his second year in office. His nominee, Suzan Johnson Cook, was not confirmed until April 2011. She resigned in October and has not been replaced.

The prayer breakfast wold have been an ideal time to announce a new nominee, but Mr. Obama offered only a vague promise that he would nominate a replacement soon.

As long as the ambassadorship remains an after-thought, religious freedom as a diplomatic goal will be a secondary priority. Mr. Obama should nominate an ambassador and also name an ambassador-at-large to address well-documented specific religious discrimination in the Middle East, Africa and Asia.