Pope Benedict, making only the second visit by a pontiff to the White House, on Wednesday urged Americans and their leaders to base social and political decisions on moral principles to create a more just society.
In a visit that coincided with his 81st birthday, the Pope also called for "patient efforts of international diplomacy to resolve conflicts" and promote progress around the world.
"I come as a friend, a preacher of the Gospel and one with great respect for this vast pluralistic society," Pope Benedict said after President George W Bush welcomed him at a ceremony that included a fife and drum band in colonial garb and a 21-gun salute.
As nearly 10,000 people applauded, Bush cited the role of faith in US life, saying, "Here in America, you'll find a nation of prayer."
Bush referred to the September 11 attacks, which the Pope will commemorate when he prays at Ground Zero, the site where the World Trade Center towers once stood.
"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," Bush said.
The Pope smiled as the crowd sang "Happy Birthday" and was treated to a large white cake inside the White House.
In his speech, he praised the United States, sprinkling it with references to the founding fathers - citing the Declaration of Independence and the first president, George Washington.
But 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 that freedom demanded "reasoned public debate".
Benedict and Bush 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 clearing the way for executions to resume for the first time since September.
As US and Vatican flags fluttered, 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.
