But official definitions of antisemitism are being debated, including in professional organizations. As columnist Jeff Jacoby points out, without any apparent skepticism, some psychologists have accused the American Psychological Association of having a rampant, unaddressed anti-Jewish hate problem ("Antisemitism is growing worse on the left. And on the right," Opinion, March 12). As a member of several APA divisions and someone sensitive to real antisemitism, I find the accusation to be nonsense.

Many of the strongest supporters of Israeli and US policies toward occupied Palestine prefer to see no difference between a) opposition to their politics and b) antisemitism, as if the two can never be distinct from each other. They resort to cries of antisemitism as a way to admonish anybody and everybody who expresses criticism of Israeli policy. This tactic is disrespectful to Jews, Jewish history, Jewish culture, and Jewish values. It is a grotesque distortion of everything Jews have faced historically, and it minimizes the much-needed recognition of real antisemitism, a growing danger. No matter one's politics, we must insist on differentiating these two meanings.

Judging from the headline on Jeff Jacoby's column -- "Antisemitism is growing worse on the left. And on the right." -- one might conclude that he sees an equal level of bias between these groups. This impression is reinforced later in his piece: "Antisemitic attitudes today run strongest among the young -- on both sides of the political spectrum. Repeat: both sides."

Yet a recent study of antisemitism among the young, conducted by professors from Harvard and Tufts universities, found that antisemitic opinions are found far more frequently among youth on the right than those on the left. Moreover, the low frequency of antisemitic opinion among left-leaning youth occurs simultaneously with their high levels of criticism of Israel's policies. These kids correctly see that opposition to antisemitism, a requirement of any decent person, doesn't preclude strongly protesting the actions of the Israeli state.

Antisemitic opinions or actions, regardless of where along the political spectrum they may occur, are intolerable. But it's useful to know where this pestilence finds its greatest support.

Memo to Christian communities, from a fellow Christian: Your Jewish friends and neighbors are wounded and alarmed by the rising tide of anti-Jewish hate that Jeff Jacoby writes about. They wonder: Will the tide keep rising? How far will it go? Could it portend a return of horrors inflicted on European Jewish communities in centuries past? If things get worse, will non-Jews stand with their Jewish neighbors against the forces of hate?

Christian communities have a responsibility to help, and a way to help. They can start by infusing their own communities with greater awareness of the history of Christian antisemitism.

The story of Western antisemitism is darker, longer, and much more Christian than many Christians are aware. Christians should learn and tell this history, with due attention to Christian responsibility, as a regular part of Christian faith practice. Christian preaching should discuss it. Christian adult and youth education programs should explain it.

This will help contain today's rising antisemitism while at long last giving Jewish communities a measure of assurance that Christians will stand with them against anti-Jewish hate.

You know a hatred is insidious when hateful rhetoric comes from both sides of the political spectrum and when anger arises against your group after innocent civilians are murdered and taken hostage on a joyous holiday. Thank you to Jeff Jacoby for describing this injustice, and thank you to reliable allies who stand up against the ancient hatred of antisemitism.