But there he was Sunday, standing at the front of a vast reception hall, declaring Islam one of the world's great religions
while encouraging leaders to disavow terrorists. And there he was Saturday night, swaying to rhythmic lyrics in Arabic, only a year after deriding Islam as a religion based in hatred and vowing to bar all Muslims from entering the United States.
Ensconced within the presidential bubble on his first foreign trip, Trump is regularly finding the view from inside is often far different than from out. It's a lesson most presidents learn sooner or later. For Trump, who ran as an outsider promising to explode political norms, the adjustment appears more abrupt.
In a major address Sunday to the leaders of 50 nations where Islam is the predominant faith, Trump veered closer than ever to the establishment views of American influence abroad, a sharp and jarring break for a man whose campaign was built upon uncensored language about America's security and role in the world.
"I stand before you as a representative of the American people to deliver a message of friendship and hope and love," Trump said. "Our vision is one of peace, security and prosperity in this region and all throughout the world. Our goal is a coalition of nations who share the aim of stamping out extremism and providing our children a hopeful future that does honor to God."
The words from President Trump and candidate Trump, particularly on Islam, were vast worlds apart.
The President's message Sunday was far closer in tone to Presidents Barack Obama and George W. Bush than to the rhetoric that electrified the Republican campaign trail and helped send Trump to the White House.
This, for example, is not something candidate Trump would have said: "This is not a battle between different faiths, different sects, or different civilizations. This is a battle between barbaric criminals who seek to obliterate human life and decent people of all religions who seek to protect it."
It may have been the most consequential speech of Trump's young presidency, offering a pathway for his still-evolving foreign policy doctrine and setting a benchmark for which he will be judged in the global fight against terrorism.
Not only was the conciliatory tone a rarity for Trump, but the speech was also delivered entirely without applause as leaders of 51 Arab and Muslim nations listened in silent, yet rapt attention.
When Obama delivered his maiden speech to the Muslim world, back in June 2009, he chose a youthful audience at Cairo University as his backdrop. Students and young activists cheered that a man named Barack Hussein Obama was standing before them as the 44th president of the United States.
Eight years later, the region is even more combustible, considering Obama delivered his speech before the Arab spring. Obama did not once utter the word terrorist or terrorism, both of which were laced throughout Trump's speech, which he boiled down to "a battle between good and evil."
Yet the most stark difference on display here this weekend was not between Trump and Obama, but Trump and Trump.
"Obviously, as president you are different," a senior White House official said Sunday. "Your role is to come and to try to do more."
In this country, which he once he scorned his predecessor for appeasing, Trump has given in to its gilded embrace. The kingdom's outsized welcome, intended to flatter a president hungry for affirmation, appeared to work.
"Words do not do justice to the grandeur of this remarkable place," Trump said during his remarks.
On Saturday, Trump touted an agreement to ship $110 billion worth of weapons to Riyadh
and displayed no apprehension at how they might be used. And during his address on combating terror, Trump decided to avoid mentioning the hardline Wahabi interpretation of Islam that originated in his host country and has informed terror groups' ideologies.
For Trump, his first trip abroad has amounted to an education in the realities of being president: the contradictory messages of diplomacy, the rigid structures of protocol, and perhaps most of all, the sticky give-and-take of making foreign friends.
Those are lessons that often put Trump at odds with the president he vowed to be on the campaign trail, one who bars all Muslims from entering the country and who cuts off ties with regimes who repress parts of their populations.
During his speech Sunday, Trump used the phrase "Islamic extremism," though the original text of his remarks referenced "Islamist extremism," a subtle difference but in the Arab world, one that matters.
Asked to clarify hours later, a White House official explained it this way: "He's just an exhausted guy."
As Trump moves on from Saudi Arabia, the presidential lessons will continue. His campaign rhetoric will again intrude when he lands Monday in Israel, where he's determined the time is not right to move the US embassy from Tel Aviv to Jerusalem, as he said he would on the campaign trail.
In Rome, he isn't likely to repeat his claim from a year ago that Pope Francis is "disgraceful" for making critical comments about Trump's plans to construct a border wall with Mexico.
At the European Union headquarters in Brussels, the open questioning of the bloc will likely be kept at a minimum. And across town at NATO, any talk of the military alliance being obsolete will disappear.
Trump's foreign tour will amount to a highlight reel of campaign rhetoric meeting global reality.
Fewer places is that reality more stark than in Iraq and Afghanistan, which remains one of the most profound challenges facing the Trump administration. Yet the President mentioned neither country in his remarks on Sunday, a reminder that his policy toward both countries remains unclear.
When he returns to the White House, a decision is waiting whether to follow the advice of his military advisers and increase the number of American troops on the ground in either -- or both -- countries. A glimpse into the still-unfolding Trump doctrine may have been offered up here Sunday, as he declared: "We will make decisions based on real-world outcomes, not inflexible ideology."
"We will be guided by the lessons of experience, not the confines of rigid thinking," Trump added, the only vague reference to the Iraq War. "And wherever possible, we will seek gradual reforms, not sudden intervention."