Speaking before a joint meeting of the US Congress in Washington on Thursday, Pope Francis tackled the woes facing the institutions of marriage and family in the United States which, he said, are facing threats "from within and without."

The Pope noted that fundamental relationships are now being called into question in America, rocking the very foundation of marriage and family. He said the people he is most concerned about are the youth, since they are trapped within "a hopeless maze of violence, abuse and despair," he said, according to the Catholic News Agency.

"How essential the family has been to the building of this country! And how worthy it remains of our support and encouragement!" the Pope said.

Because of the problems confronted by the youth nowadays, many of them decide not to get married. Pope Francis blames this problem on the "culture which pressures young people not to start a family, because they lack possibilities for the future."

"Yet this same culture presents others with so many options that they, too, are dissuaded from starting a family," he added, as he took a jab against the trend of being "childless-by-choice."

This was the first time a pope addressed a joint meeting of the US Congress. Pope Francis took advantage of the opportunity to remind American lawmakers of their personal and social responsibilities.

"Your own responsibility as members of Congress is to enable this country, by your legislative activity, to grow as a nation... You are called to defend and preserve the dignity of your fellow citizens in the tireless and demanding pursuit of the common good, for this is the chief aim of all politics," he said.

"A political society endures when it seeks, as a vocation, to satisfy common needs by stimulating the growth of all its members, especially those in situations of greater vulnerability or risk. Legislative activity is always based on care for the people," he said. "You are asked to protect, by means of the law, the image and likeness fashioned by God on every human face."

The Pope cited four renowned American historical figures who are worth emulating for their "hard work and self-sacrifice to build a better future." He cited Abraham Lincoln, Martin Luther King Jr., Dorothy Day, and Thomas Merton.

"Four individuals and four dreams: Lincoln, liberty; Martin Luther King, liberty in plurality and non-exclusion; Dorothy Day, social justice and the rights of persons; and Thomas Merton, the capacity for dialogue and openness to God. Four representatives of the American people," he said.

In his address, the Pope also condemned the death penalty and the weapons trade, as he called for their abolition worldwide.

On the issue of immigration, the Pope reminded the American people that most of them were once foreigners, too. "We, the people of this continent, are not fearful of foreigners, because most of us were once foreigners," he said. "I say this to you as the son of immigrants, knowing that so many of you are also descended from immigrants."

Recalling early American history, the Pope noted that the American natives' first contacts with foreigners were often violent. But Pope Francis stressed that the past must not be repeated "when the stranger in our midst appeals to us."

On the refugee crisis, Pope Francis acknowledged that tough decisions had to be made. However, he reminded American political leaders that they must see the refugees "as persons, seeing their faces and listening to their stories, trying to respond as best we can to their situation."

He underlined the Golden Rule, explaining that if Americans want opportunity and security, they must give these to others. "This Rule points us in a clear direction. Let us treat others with the same passion and compassion with which we want to be treated. Let us seek for others the same possibilities which we seek for ourselves," he said.

"The yardstick we use for others will be the yardstick which time will use for us," he said.

Later on Thursday, Pope Francis flew to New York and delivered an address at St. Patrick's Cathedral in a gathering attended by the American clergy. There, the Pope tackled the issue of sexual abuse that has hounded the Catholic Church in the US for the past few decades.

"I know that, as a presbyterate in the midst of God's people, you suffered greatly in the not distant past by having to bear the shame of some of your brothers who harmed and scandalised the Church in the most vulnerable of her members," he said.

Pope Francis expressed unity with those who suffered from the scandals, encouraging them to still carry out their vocations "in joy."

"I accompany you at this time of pain and difficulty, and I thank God for your faithful service to his people," he said, adding that they have "come forth from the great tribulation."

New York is the second of three cities which Pope Francis will visit during his Sept. 22 to 27 visit to the US.