Last month, Ambassador Dan Gillerman of Israel left office after five years at the United Nations. Awaiting the change in guard to the new Israeli ambassador to the United Nations, the first woman to hold the seat, it makes sense to take stock of the past five years of Israel-U.N. relations.

Mr. Gillerman arrived to a post-September 11, 2001, and pre-Iraq world. The Road Map for Peace between Israelis and Palestinians had been introduced but not yet internationally agreed upon.

In a post-Cold War climate, the dollar fell and the euro rose while the struggle for power at the United Nations between those holding the purse strings and those with the largest number of votes became increasingly divisive.

Ideological divides between “the West” and “the rest” threatened the organization’s ability to function by consensus. Shifting alliances among liberal democracies and regional players presented new opportunities and challenges to Israel’s goal of normalized status at the United Nations.

Arab states used the organization in their attempts to delegitimize Israel’s right to exist as a Jewish state. Israel’s response was to focus on proactive international diplomacy. By striving to be treated as a “normal” democracy, it cultivated the credibility necessary to contribute to various diplomatic efforts rather than only those related to its own conflicts.

One critical change in technicalities helped make such accomplishments possible. Long sought permanent acceptance into the regional group of Western and other like-minded countries finally allowed Israel to run for elections in political bodies like the General Assembly and the Economic and Social Council. The country was finally able to request candidature for Security Council membership in 2018 and initiated its first-ever successful General Assembly resolution.

Consequently, European and other democratic countries began to recognize Israel’s contribution. This was due in no small part to the fact that they were directly confronted by terrorism’s impact on their own societies and therefore more empathetic to Israel’s security challenges. Not only did this affect daily interaction among diplomats at the United Nations, but it also affected their countries’ votes on issues related to Israel, anti-Semitism, and human rights.

Finally, in 2004, three years after the infamous Durban World Conference against Racism, the United Nations held its first international conference on anti-Semitism. The secretary-general at the time, Kofi Annan, echoed the already adopted declaration: “International developments or political issues, including those in Israel or elsewhere in the Middle East, never justify anti-Semitism.” Another unprecedented accomplishment occurred when, for the first time in 60 years, the General Assembly recognized the horrors of the Holocaust and condemned Holocaust denial. And, the Security Council condemned President Ahmadinejad of Iran directly for Holocaust denial and for violent rhetoric threatening to destroy Israel.

Politically speaking, Security Council negotiations trump the General Assembly because they can provide diplomatic and legal solutions to military conflicts. In the case of the Lebanon war, the council brokered a ceasefire and set the terms for follow-up discussions to address tensions. Israel accomplished additional diplomatic feats in the council and other areas through precedent-setting acknowledgement of Israeli security concerns and regret over the loss of Israeli civilian life due to Palestinian terrorist attacks. The change in U.N. administration under the Secretary-General Ban Ki-moon also saw a decrease in polarizing rhetoric.

New challenges extend beyond Mr. Gillerman’s reign. On the frontlines of international humanitarian and human rights law, Israel must continually prove itself in the battle for political and legal legitimacy. Although Mr. Annan acknowledged that the long-criticized Commission on Human Rights had a “credibility gap,” partly due to its bias against Israel, attempts at reform didn’t rectify the problem. The newly created body has been deemed even worse.

It is hard to predict how Ambassador Gabriela Shalev’s term will evolve as events in the Middle East often dictate decisions at the United Nations, even when negotiations are unrelated. For those seeking to improve the United Nations, this is challenging, as it holds change in the system hostage to politics on the ground. It is our hope that the United Nations can more positively affect Middle East politics and thus improve relations with Israel as well. However, to accomplish this goal, it must reflect a more accurate view of reality rather than continue to serve as a political battlefield.

Mr. Gillerman was known for his warmth and sense of humor in the face of such complexity, as well as for his ability to reach out personally. Under his leadership, staff at the Israeli Mission frequently said that it was their job not only to represent Israel to the United Nations but also to represent the United Nations to Israel.

Already speculation of the president of the General Assembly, Miguel d’Escoto Brockmann, attending a dinner next week with Mr. Ahmadinejad are dimming our hopes for a better outlook. Nonetheless, we hold out hope that circumstances will permit Ms. Shalev to continue advancing Mr. Gillerman’s lofty directive in a positive light.

Ms. Sanchez is the B’nai B’rith International Director of United Nations Affairs.