Harvard professor Bryan Hehir once famously warned that government officials who deal with the role of religion in foreign policy should see their work as akin to brain surgery — necessary, but fatal if not done well. That thesis will be tested as President Trump concludes his journey to Saudi Arabia, Israel and the Occupied Territories, and the Vatican, all on the heels of his worst week as president.

I should know what the stakes are. I was Secretary of State John F. Kerry’s religion adviser as the special representative for religion and global affairs and founding director of the Office of Religion and Global Affairs. I worked in all three spaces Trump will be addressing on this trip: relations with Muslims around the world, Middle East peace and relations with the Vatican. When Kerry met with religious actors or encountered religious dynamics around the world, he had expert resources to draw on to gain a deeper understanding. That is not the case for Trump.

According to Philip Rucker and Ashley Parker’s Washington Post piece last week outlining the various tutorials Jared Kushner prepared for the president ahead of the trip, there seemed to be no presidential tutorial on the religious dynamics of each visit. (Indeed, it appears the first son-in-law reduced every pertinent issue to a one-page paper.) Yet the religious dynamics Trump has and will encounter are among the most complex on the planet. The thought of a one-pager explaining the intricacies of Islam, Judaism and Christianity is so painfully frightening it leaves one speechless.

What are the risks on each stop and how could Trump have been better prepared? Consider each of his three stops.

Some of the lessons he might have learned about Saudi Arabia from knowledgeable staffing would be that there is limited utility in grand U.S. presidential speeches, or in symbolic acts of orb-handling. Addresses must be followed by strategic engagement and action. In 2013, I spoke at a large interfaith gathering in Europe, sponsored and funded by the Saudis. I found myself on the final panel of speakers of the multiday event giving the penultimate speech, followed by a senior Saudi government official. When he finished his remarks, he pinioned around me, refusing to shake my hand, but whispered over his shoulder to me expressing his frustration with the poor followup to President Barack Obama’s 2009 Cairo speech, “Tell your president we don’t need more pretty presidential speeches, we need action,” he said.

Then there’s Israel, the last place on earth fit for flashcard diplomacy. Trump’s campaign language has cast the peace process there in terms of a deal, but the complexities of a possible peace agreement cannot be reduced to a New York real estate deal. Due likely to a lack of expert staffing and sufficient grasp of the issues at hand, Trump’s visit essentially neglected the question of a peace agreement altogether, with the president never so much as mentioning a Palestinian state.

On my first visit to Jerusalem as a diplomat, I was welcomed warmly by one of the many Christian Patriarchs there.  “Dr. Casey, it is so good to meet you,” he said.  “We’ve been waiting for you for 40 years!” I took him to mean that Middle East peace required more than a quick back of the envelope deal. Indeed, without an understanding of the maddeningly complex political and religious contours of the problem, there were no deals to be had.

Further complicating matters is the aroma of anti-Semitism wafting from both the campaign and early White House days, combined with the leaking of sensitive intelligence linked to Israeli sources, neither of which inspires confidence among some Israelis. We might be tempted to count this leg of the trip as a success, given the absence of any massive misstep — though Trump did sign the Holocaust museum Yad Vashem’s Book of Remembrance with a bizarre, yearbook-like autograph, as opposed to Obama’s somber, thoughtful note. It could have been worse, and it could have been much better.

Today, Trump will travel to Rome to meet with Pope Francis, with whom he shared a strange exchange of barbs during the election. When he gets to the Vatican, the president faces two challenges. First, he needs to somehow resolve the tense relationship he created with the pope during the last campaign. It won’t be easy to smooth over with small talk: There is a huge gulf between the two leaders on climate change and the global refugee crisis, so little to chat about in terms of agreed-upon policy. But Vatican officials know very well how to manage global leaders with whom they disagree and with leaders who do not really understand the Roman Catholic Church. But to settle for an awkward civility instead of a productive diplomatic relationship would be a tragic failure on the president’s part.

Second, based on the Vatican’s successful diplomatic work with the Obama administration on many priority issues (including our normalization of relations with Cuba), my hunch is they would like a career ambassador from the United States — that is, an experienced and capable diplomat with whom they can continue to work toward actionable goals. That the Trump administration has nominated Callista Gingrich shows the administration has either not picked up on that desire or has decided to not honor it. It is widely acknowledged that the pope has vastly strengthened the Vatican diplomatic corps, and that he deeply appreciated the working relationship with former U.S. Vatican ambassador Kenneth Hackett and Kerry. To prioritize scoring domestic political points over strengthening the ties between the Vatican and the United States is, therefore, an extraordinary missed opportunity.

When I accompanied Kerry on his first trip to the Vatican to meet with his newly appointed counterpart, Vatican Secretary of State Cardinal Pietro Parolin, I showed Kerry an address Francis had just given to the Vatican diplomatic corps. I noted the deep overlap between our foreign policy goals and those of the pontiff. Kerry saw the opportunities the new pope offered, and he initiated a new and fruitful diplomatic partnership resulting in, among other things, a strong international climate change agreement. That Trump does not seem to have staff to prepare him to build on this legacy is tragic. A career ambassador would go a long way in mitigating the damage from Trump’s campaign spat with Francis.

The risks attached to this trip are large. The president could have built a capacity to navigate these complex religious and political dynamics, but he has not done so yet. Having scrubbed or lost almost all the expertise in the U.S. government to assess religious landscapes, the president may learn that his multistate tour of world religions is, in fact, a dangerous trip into the abyss. My hope is that it will not take a diplomatic crisis from this trip to persuade the Trump White House to build its own expertise on religion at the State Department.