Antisemitism is often referred to as "the oldest hatred." It is certainly the most enduring. However, like all diseases, the disease of anti-Jewish hatred must at some point be contained. It simply must not be allowed to persist. Not only for the sake of Jews across the world, but for humanity itself. For all, antisemitism poses a real and present threat.When granting equal rights to the Jews of France, Napoleon Bonaparte said “the national attitude towards Jews is the barometer of society’s civilization.” This is just as true today as it was two centuries ago.Throughout time, Jews have been among the most loyal citizens, wherever they have lived. They have championed the institutions and laws of these countries. They have done their utmost to integrate into the societies they lived in, to win trust and acceptance. As a result, Jews have typically achieved beyond their numbers, becoming prominent figures in science, politics, culture, finance, communications and beyond.Sadly, this has invariably made Jews the natural target for those wishing to dismantle the fabric of society. As a powerful symbol of society’s foundations, Jews have become a magnet for vilification from extremists on both the Right and the Left.Rejection of the Jews became a rejection of world order. They were always the first target, but by no means the last. The Nazis annihilated one third of the Jewish people, six million Jews, but in total, more than 60 million people were killed during the Second Word War. What began as persecution of the Jews led the world to stand at the gates of destruction. If extremists are not stopped in their antisemitic tracks, they will eventually target wider society, taking over executive power in their states.Therefore, just as world leaders gather each year in Davos, to discuss the state of the global economy, and in Munich, to discuss global security, they should also come together to discuss global morality, and specifically antisemitism as the benchmark for this. Worryingly, we find that the world is currently failing this crucial litmus test.As President of the European Jewish Congress, I can only offer a dark picture of Jewish communities hiding behind high fences and thick security doors. The almost unbelievable reality is that just 75 years after the Holocaust, humanity’s darkest hour, Jews are again afraid to walk the streets of Europe wearing Jewish symbols, while synagogues and cemeteries are regularly attacked and desecrated.The statistics are perhaps even more alarming. More than 80% of Jews feel unsafe in Europe today, while 40% are considering leaving Europe entirely and in recent years, as much as 3% have done so annually. At the current rate, after 3000 years of European Jewish life, in just a few generations from now, there will be few if any Jewish communities left in Europe.We find ourselves at European Jewry’s eleventh hour. We must change course and there is plenty to be done. Firstly, we must educate – about the Holocaust and about the dangers of antisemitism, racism and xenophobia. They must be part of every educational curriculum from an early age.Secondly, we must introduce meaningful legislation and thirdly, fully enforce it. In this regard, there is from where plenty to learn good practice. Germany adopted stringent legislation two years ago combating online hate speech. A recent Executive Order in the United States will restrict federal funds to higher education institutions which tolerate antisemitism.In the UK, a task force combined of law enforcement agencies, legal institutions and civil society, coordinates effectively to act against antisemitism. A few weeks ago, the French National Assembly passed a resolution acknowledging that anti-Zionism is antisemitism.And in Russia – where the rates of antisemitism are among the lowest – law enforcement, judicial and political authorities treat antisemitic incidents with the utmost seriousness.The Fifth World Holocaust Forum – held today in Jerusalem – gives more than 45 world leaders the opportunity to learn from one another, to discuss, plan and work for a better future. It is a chance to move the needle on antisemitism, to begin to put an end to it once and for all, and to steer global morality back on course.For the sake of all humanity.The author is the president of the World Holocaust Forum Foundation and the European Jewish Congress.