Pope Benedict XVI today urged Americans and their leaders to base their political and social decisions on moral principles and create a more just society.
The pope also called for "patient efforts of international diplomacy to resolve conflicts" and promote progress around the world in an address to President George W. Bush at the White House on the first full day of his US visit.
"I come as a friend, a preacher of the Gospel and one with great respect for this vast pluralistic society," Pope Benedict said in a speech after Mr Bush welcomed him at a ceremony that included a fife and drum band in colonial-era garb and a 21-gun salute.
At the outdoor ceremony attended by more than 9,000 people, Bush cited the role of faith in US life, saying "Here in America, you'll find a nation of prayer."
Mr Bush also referred to the September 11th, 2001 attacks, which the pope will commemorate when he visits New York with a prayer at the World Trade Center site.
"In a world where some invoke the name of God to justify acts of terror and murder and hate, we need your message that God is love. And embracing this love is the surest way to save man from falling prey to the teaching of fanaticism and terrorism," Mr Bush said.
The pope, marking his 81st birthday, praised American society, sprinkling his speech with references to the founding fathers - citing the Declaration of Independence and the first president, George Washington.
He made no specific references to issues such as abortion and the Iraq war, avoiding anything that could be seen as taking sides in the presidential campaign apart from saying freedom demanded "reasoned public debate".
Pope Benedict and Mr Bush, who spoke privately after the ceremony, oppose abortion and embryonic stem cell research but differ on the Iraq war and capital punishment. As the pope spoke, the US Supreme Court, led by Bush appointee Chief Justice John Roberts, issued a ruling that cleared the way for executions to resume for the first time since September.
Instead, Pope Benedict concentrated on America's religious roots, which he said were a driving force in a process that "forged the soul of the nation" and won world admiration.
It was Mr Bush who referred to abortion, a hot-button issue particularly with the presidential election in November.
"In a world where some treat life as something to be debased and discarded, we need your message that all human life is sacred ... ," Mr Bush said.
The pope said freedom "is not only a gift but also a summons to personal responsibility" toward the less fortunate at home and around the world.
"Democracy can only flourish, as your founding fathers realized, when political leaders and those whom they represent are guided by truth and bring the wisdom born of firm moral principle to decisions affecting the life and future of the nation," the he said.
Pope Benedict, who will address the United Nations as part of his first trip to the United States as pope, was only the second pontiff to visit the White House.
Looking forward to his UN speech, the pope said the need for global solidarity is "as urgent as ever if all people are to live in a way worthy of their dignity" and secure a place at "that table which God's bounty has set for all his children".
In a possible reference to US criticism of the world body, the pope said:
"I am confident that this concern for the greater human family will continue to find expression in support for the patient efforts of international diplomacy to resolve conflicts and promote progress."
The pope ended his speech by saying "God bless America" in a raised voice.
Later on Wednesday, the pope was addressing US bishops at the National Shrine of the Immaculate Conception, where he was to discuss the scandal of sexual abuse of children by priests, which he said had left him "deeply ashamed".