Religious freedom is one of America's most "precious possessions," Pope Francis has told President Barack Obama.

The Pope spoke at the White House after arriving in Washington the day before and he spoke on an issue when some believers feel religious freedom is under siege in a rapidly secularizing country.

He echoed appeals by the U.S. bishops on the issue of religious freedom, Catholic News Agency reported.

"With countless other people of good will, they are likewise concerned that efforts to build a just and wisely ordered society respect their deepest concerns and the right to religious liberty," Francis said Sept. 23.

"That freedom reminds one of America's most precious possessions.

"And, as my brothers, the United States Bishops, have reminded us, all are called to be vigilant, precisely as good citizens, to preserve and defend that freedom from everything that would threaten or compromise it."

The pontiff told Obama: "All are called to be vigilant, precisely as good citizens, to preserve and defend that freedom from everything that would threaten or compromise it."

Obama also spoke of religious liberty noting that the beheading by Islamic State extremists of Coptic Christians in Libya.

"You remind us that people are only truly free when they can practice their faith freely," Obama said.

"Here in the United States, we cherish religious liberty. It was the basis for so much of what brought us together. And here in the United States, we cherish our religious liberty, but around the world, at this very moment, children of God, including Christians, are targeted and even killed because of their faith."

"Believers are prevented from gathering at their places of worship. The faithful are imprisoned, and churches are destroyed,"said  the president.

"So we stand with you in defense of religious freedom and interfaith dialogue, knowing that people everywhere must be able to live out their faith free from fear and free from intimidation."

Speaking at the White House on Sept. 23 before thousands of people who gathered the Pope also spoke on immigration and the environment.

"As a son of an immigrant family, I am happy to be a guest in this country, which was largely built by such families," he said.

The pontiff praised American for supporting "the efforts of the international community to protect the vulnerable in our world and to stimulate integral and inclusive models of development" so that all can share in global prosperity.

Speaking before the Pope, President Obama noted how 20,000 people gathered on the White House lawn served as only a small reflection of the "deep devotion of some 70 million American Catholics."