In the face of various threats to religious freedom in the United States, most notably the Supreme Court ruling allowing homosexual marriages in the country, Pope Francis urged all Americans to defend their religious rights.

Addressed immigrants and Hispanic Americans at Philadelphia's Independence Mall on Saturday, the leader of the Roman Catholic Church called on all Americans and all religions to fight all efforts to limit religious freedom, according to a report from the Catholic News Agency (CNA).

"May this country and each of you be renewed in gratitude for the many blessings and freedoms that you enjoy. And may you defend these rights, especially your religious freedom, for it has been given to you by God himself," the Pope said.

Pope Francis defined religious freedom as "the right to worship God, individually and in community, as our consciences dictate," CNA said.

He also called on Americans to oppose all moves to use religion to promote violence, with the threat of extremist groups such as the Islamic State of Iraq and Syria (ISIS) looming across the world.

"In a world where various forms of modern tyranny seek to suppress religious freedom, or try to reduce it to a subculture without right to a voice in the public square, or to use religion as a pretext for hatred and brutality, it is imperative that the followers of the various religions join their voices in calling for peace, tolerance and respect for the dignity and rights of others," Pope Francis said.

In the same speech, the Pope likewise acknowledged the importance of Philadelphia, particularly the National Constitution Center and the Liberty Bell Center, in America's history. The Pope said he recognised the symbolism of speaking about religious freedom in these places.

"It was here that the freedoms which define this country were first proclaimed," Pope Francis said, citing the Declaration of Independence.

"Those ringing words continue to inspire us today, even as they have inspired peoples throughout the world to fight for the freedom to live in accordance with their dignity," he added.