President Barack Obama welcomes Pope Francis to the White House. (CNA/Getty Images)

WASHINGTON, DC (CNA/EWTN News) - Pope Francis Wednesday reminded U.S. president Barack Obama that religious freedom is one of America's most "precious possessions," while lauding the nation's Catholics their work toward a society marked by tolerance and inclusivity.

"With countless other people of good will, (American Catholics) are likewise concerned that efforts to build a just and wisely ordered society respect their deepest concerns and their right to religious liberty," the Pope said Wednesday, addressing the U.S. commander-in-chief at the White House in Washington, D.C.

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

Echoing the appeals by the U.S. bishops on the issue of religious freedom, the pontiff told President 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."

Pope Francis also stressed the role American Catholics have played in building a tolerant and inclusive society in the nation, one which safeguards of individuals and communities, while "rejecting every form of unjust discrimination."

In his remarks prior to the pontiff's, President Obama noted how the 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."

The Pope's meeting at the White House, marking the first major event of his visit to the U.S. Capital, comes at a time of uncertainty with regard to religious of freedom in the country.

Affecting many Catholic as well as other religious institutions, the Obama administration's 2012 HHS mandate requires institutions to provide contraceptive services, often failing to offer exemptions to those who oppose the bill on religious grounds.

There are also concerns regarding the religious rights of those who oppose same-sex marriage after the U.S. Supreme Court ruled earlier this year to legalize marriage between gay couples across all fifty States.

Pope Francis' Sept. 23 speech to President Obama also addressed the issue of climate change, and acknowledged US's commitment to seeking solutions to air pollution.

"Accepting the urgency, it seems clear to me also that climate change is a problem which can no longer be left to a future generation," the Pope said.

He said this is a "critical moment in history" with regard to caring for our "common home."

Citing his encyclical on the environment, Laudato Si'," Pope Francis stressed the need for continued changes in the areas of "sustainable and integral development."

"Such change demands on our part a serious and responsible recognition not only of the kind of world we may be leaving to our children, but also to the millions of people living under a system which has overlooked them."

"Our common home has been part of this group of the excluded which cries out to heaven and which today powerfully strikes our homes, our cities and our societies."

The Pope cited Martin Luther King, saying "we have defaulted on a promissory note and now is the time to honor it."

Inspired by the certainty that the Creator does not abandon his creatures, the Pope said, we as Christians "wish to commit ourselves to the conscious and responsible care of our common home."

"The efforts which were recently made to mend broken relationships and to open new doors to cooperation within our human family represent positive steps along the path of reconciliation, justice and freedom," the Pope said.

"I would like all men and women of good will in this great nation to support the efforts of the international community to protect the vulnerable in our world and to stimulate integral and inclusive models of development, so that our brothers and sisters everywhere may know the blessings of peace and prosperity which God wills for all his children."

Pope Francis also expressed his appreciation to Obama for the welcome he had received in the U.S., while lightly alluding to the question of immigration. He recalled that America is a country largely built on immigrant families, like his own Italian family who settled in Argentina.

Concluding his White House address, the Pope said: "Mr. President, once again I thank you for your welcome, and I look forward to these days in your country. God bless America!"

The Sept. 22-28 apostolic journey to the U.S. marks Pope Francis' first on America soil.

In addition to the meeting with President Obama at the White House, the agenda for the Pope's visit to the U.S. capital includes the canonization of Blessed Junipero Serra at the National Shrine of the Immaculate Conception, and a visit to the US Congress.

The Pope's visit will also include an address at the United Nations Headquarters in New York City, and will culminate with his presence in Philadelphia for the World Meeting of Families.