The U.S. Constitution prohibits "an establishment of religion," but U.S. presidents have long paid tribute to the importance of faith in a divine power.
"Every free government is imbedded soundly in a deeply-felt religious faith, or it makes no sense," said Dwight D. Eisenhower, speaking at the first National Prayer Breakfast in 1953. Since then, all presidents have spoken at the annual event, often highlighting their own faith or the role of prayer in their personal lives.
This year's breakfast will give President Trump another opportunity to burnish his less than perfect reputation as a religious man. The White House on Wednesday confirmed that he will speak at the event, which by tradition is co-chaired by a Republican and Democratic member of Congress.
The breakfast is meant to provide a break from partisan acrimony.
"Sometimes it feels as though only divine intervention can bring Republicans and Democrats together in Washington," wrote Sens. Chris Coons, D-Del., and John Boozman, R-Ark., the hosts of this year's breakfast, in a jointly signed column in the Washington Examiner.
It doesn't always work. Ben Carson used his speech at the 2013 Prayer Breakfast to make a blistering attack on President Obama, who was seated just a few feet away, and thereby launched his own political career. A principal speaker this year will be Rick Warren, pastor of the Saddleback Church network in California. Warren has attempted to be nonpartisan in his ministry and offered a prayer at Obama's inauguration in 2009.
"I think it is an important thing," Warren said in a Facebook video, referring to the breakfast, "particularly right now, after this last election and campaigning, which has really divided America." He cited the Sermon on the Mount, in which Jesus called on his followers to be peacemakers.
"Who wants to bring peace? As Christians, we are called to do that," Warren said.
With his own speech at the breakfast, Trump will have to choose whether to attempt some reconciliation with his political opponents or confront them, as he has done in the past week, as Democrats in Congress resisted his Cabinet nominations.
Some advocates of LGBT rights have feared that Trump will use his speech at the prayer breakfast to announce a new executive order providing greater protection for Christian conservatives who oppose same-sex marriage and other accommodations for LGBT individuals. Those concerns were somewhat alleviated by a White House announcement on Tuesday that the Trump administration would continue to enforce a 2014 executive order signed by Obama that barred discrimination against LGBT people working for federal contractors. White House officials, however, have not ruled out the possibility of another executive order on the issue.
Trump's order last week suspending the admission of refugees and temporarily barring immigration from seven majority-Muslim countries could also be an issue at the prayer breakfast. The order has aroused stiff and vocal opposition from many Christian groups.
Hundreds of foreign dignitaries will be on hand at the breakfast, including King Abdullah II of Jordan, a country currently burdened by a huge influx of Syrian refugees. Abdullah met earlier in the week with Vice President Pence and Defense Secretary James Mattis, but his encounter with Trump at the breakfast will be their first meeting. Trump has made clear he would like more assistance from countries like Jordan in the fight against ISIS, but Jordanian authorities worry that Trump's promise to move the U.S. Embassy in Israel to Jerusalem could make it politically difficult to show more support for the United States.