One of the possible pitfalls of Trump’s upcoming foreign trip  is the speech he intends to give in Saudi Arabia on Islam:
A speech was added in Saudi Arabia to provide an “inspiring yet direct” message to the Islamic world, according to national security adviser H.R. McMaster. That’s an echo of Trump’s predecessor Barack Obama, who addressed Muslims in Cairo in his first major speech on foreign soil.
A second address in Israel, which local newspapers reported would take place at the ancient archeological site of Masada, was moved indoors to a museum. Transporting Trump to the mountaintop overlooking the Dead Sea would have required the use of a cable car.
Both speeches were being drafted by Trump’s policy adviser Stephen Miller, who helped write Trump’s convention and inaugural addresses, with input from the large collection of advisers who are helping to plan the trip: son-in-law and senior adviser Jared Kushner, McMaster and deputy national security adviser Dina Powell.
Miller is a dubious choice for writing the first speech because of his views on Islam , but the speech itself seems ill-advised no matter who is writing it. A comparison with Obama’s Cairo speech is instructive. Obama delivered that speech very early in his presidency, just as Trump will be doing, and he managed to say just enough to raise expectations that would never be fulfilled. Everything Obama did from then on was judged against what people thought he had been promising in the speech, and invariably his policies fell short. If Trump wants to offer an “inspiring” message, his later policies are almost certain to prove disappointing. We have been told  that the “speech is intended to unite the broader Muslim world against common enemies of all civilization,” but that is hard to credit when the U.S. under Trump is taking sides in wars that pit Muslims against Muslims.
Obama had a much more receptive audience, because he was not perceived to be hostile to Muslims as such, but Trump is perceived that way because he usually is. Trump will have a harder task than Obama did, because he first has to assuage fears about his hostility but still has to take hard-line positions to satisfy his supporters at home. That would be a difficult balancing act for any politician to pull off, and I doubt that Trump is capable of doing it. Since Trump isn’t exactly known for his grasp of nuance, he is likely to indulge in excessive flattery of his hosts or commit multiple diplomatic errors (or both).
There is also something misguided in having American presidents come to predominantly Muslim countries to tell them about their own religion. This has been true when Bush and Obama wanted to hold forth on this subject, and it is still true. At best, anything our president says will come off as boilerplate or condescending, so that the speech is quickly forgotten and has no effect. At worst, he is going to insult the intended audience and provoke a backlash, and that will make things worse than they were before. The location for the speech is also unfortunate, since Riyadh is at the heart of one of the most obnoxious strains of Islam in the world, and giving this particular speech there could be interpreted as giving a boost to Wahhabism, which is the last thing that Trump or any other president should do while visiting Saudi Arabia.
The problem with Trump’s Islam speech is related to the administration’s view of what Trump is trying to do with his first trip abroad. According to AFP, the White House sees  the trip as a way to promote unity among different religions:
US President Donald Trump will urge unity between the world’s major faiths on an ambitious first foreign trip that will take him to Saudi Arabia, the Vatican and Jerusalem, the White House said Tuesday.
While that may sound like a nice sentiment, this isn’t something that politicians can help bring about with the best will in the world. Very few people are going to take Trump’s appeal seriously in any case, because hardly anyone thinks that he takes religious faith seriously in the first place. It would be one thing to have the president argue for religious tolerance, or at least to argue against sectarianism and violence, but for a politician to “urge unity” among religions that have real, deep differences of belief is both misguided and sure to be rejected by all sides. No president is suited to such a role, and Trump is almost uniquely unsuited to it.