Jewish life in Europe is fast becoming unsustainable. A quarter of European Jews are afraid to wear distinctive Jewish clothing or jewelry, and 23% are afraid to go to Jewish events or venues. Nearly a third of all European Jews are currently considered emigrating. A major 2013 study found that two thirds of European Jews feel anti-Semitism has had a negative impact on their lives.

Against this background of constant, grinding anti-Semitism, the latest horror occurred. On Saturday, May 24, 2014, a gunman entered the Jewish Museum of Belgium and opened fire, killing four people. The victims were a 23 year old employee of the museum, a Tel Aviv couple in their 50s who were vacationing in Brussels, and a museum volunteer. Although Belgian police arrested a man soon after the murders, he was soon released, and the police continued to search for the two men seen at the scene of the shooting.

In the hours after that attack, Belgian authorizes were quick to condemn not only the murders, but the climate of anti-Semitism that had allowed them to occur. Belgium’s Interior Minister immediately announced that security at all Jewish sites in Belgium had been increased. Prime Minister Elio Di Rupo made a statement in support of Belgium’s 42,000-strong Jewish community, saying all Belgians are united with them.

While their words are welcome, they are clearly not enough to assuage Belgian Jews’ fears; Belgium has recorded rising levels of anti-Semitism, with a 30% jump in recent years, reflecting a community increasingly under siege

Prime Minister Benjamin Netanyahu blamed the attack on the growing climate of fear that is dogging Jews across Europe, calling it “the result of constant incitement against Jews and their state. Slander and lies against the State of Israel continue to be heard on European soil even as the crimes against humanity and acts of murder being perpetrated in our region are systemically ignored.”

“The spirit of Jewish people, the Jewish community here in Belgium, is really very, very low,” confirmed Raya Kalenova, a Brussels-based Executive Vice President of the European Jewish Congress. “They do not even report anti-Semitic attacks. They feel that it is useless to report and they do not feel protected. For sure, the general atmosphere is not good here in Belgium, especially because of anti-Israeli sentiment.”

That sentiment is growing. Three weeks before the Jewish Museum attack, Brussels was home to an anti-Jewish rally organized by the hard-core anti-Zionist MP Laurent Louis. The rally, featuring Holocaust deniers and the French anti-Israel comedian Dieudonné, was prohibited by the city authorities, but it managed to attract hundreds of supporters before being broken up by police. And at the time of the attack, Brussels was hosting another anti-Israel event, a major concert and rally in the central Parc du Cinquatenaire, which featured denunciations of the Jewish state.

As we mourn the shooting at the Jewish Museum of Brussels, what can we do to help combat the climate of hate that is stalking Jewish communities across Europe and beyond? How can we properly mourn these four victims, murdered in the heart of a major European capital simply for being Jews?

Here are five suggestions:

1. Stand together.

The shooting at the Jewish Museum of Brussels reminds us that no matter where we are, we are part of one Jewish people. Make an effort to feel that even though the victims may have been far away or different from us in language or in some other way, they are still our brothers and sisters. Their tragedy is our tragedy too.

2. Do good in their memory.

The Jewish answer to catastrophe is to respond with good. When we see evil in the world, the Torah asks us to work to increase the kindness and righteousness we put into the world, instead.

In the merit of the souls of those who were killed in the Jewish Museum of Belgium, consider taking on a new mitzvah, such as lighting Shabbat candles, or deciding to read a new Jewish text. Brainstorm with your family about a project you can take on to help others in their memory.

3. Fight hatred with pride.

The best defense against anti-Semitism is not being afraid to embrace Judaism and to learn more about it. Do something to deepen your connection with Judaism, Israel and the Jewish people today, in memory of the victims in Belgium who were killed because they were Jews.

4. Stand up to anti-Semitism.

Don’t be afraid to call anti-Semitism what it is: an irrational hatred of the Jewish people. Whether it’s applying an impossible double standard to the Jewish state, or belittling or slandering Jewish people or practice, take a stand against anti-Jewish statements.

Resist the urge to rationalize this act. Nothing can ever justify the murder of innocent people.

5. Volunteer in your community.

It’s not only Jews in Belgium who need our help. In the merit of those who were murdered in Brussels, take a look at your own local Jewish community. What needs are there in your own local neighborhood?

Try volunteering close to home. In addition to aiding others, turning to our communities in times of crisis can help us create new connections with our fellow Jews, and also can help us strengthen ourselves.