Elie Wiesel is one of my greatest heroes, and I’ve been lucky to have a warm friendship with him. I would rarely consider disagreeing with such a moral giant, one of the foremost Jewish personalities of modern times and who has had such a profound impact on my life.

Except on one issue. Hate.

In many conversations, Wiesel (or as I call him, Reb Eliezer) has told me that I am wrong on the subject of hatred. We can’t hate even our enemies; it seeps into our blood and poisons us. But what happens when it is not our enemies but the enemies of humanity itself, the enemies of all that is good, the nemesis of morality that we hate? What are we to feel for an organization like Hamas if not hate?

How are we supposed to carry out our moral resolve to fight a genocidal thugocracy sworn, like the Nazis, to the extermination of the Jewish people if we don’t detest and loathe them? How are we supposed to react to a terror organization that perpetrates honor killings against innocent Palestinian women, uses Arab children as shields for its missiles, and teaches Palestinian youth that rather than living a long and productive life they are better off blowing themselves up? Wiesel is one of the softest, most noble souls I have ever met, so I understand his reluctance to harbor hatred. And I can understand that saintly souls like him refuse to hate even wicked murderers.

But for the rest of us mortals, especially political leaders sworn to uphold the world order, I believe that the greatest moral failure of our time is a refusal to hate evil. Hatred of evil implies both the right to make judgments as well as a belief in moral absolutes.

Because Lincoln hated the abomination of slavery he fought to stop it. As he said in 1854 in Peoria, “I can not but hate slavery. I hate it because of its monstrous injustice.”

Churchill famously said, “I hate nobody except Hitler,” inspiring a nation to fight the monster. The French, who did not hate Hitler, collaborated with him instead.

Compassion for victims’ suffering does not go far enough. Hating the perpetrators will generate the necessary action to stop their orgy of murder. While innocence should evoke compassion, evil should evoke only contempt.

Many today seek to understand, rather than resist, evil. They excuse the murderous actions of Hamas by speaking of Palestinian humiliation. Is it motivated by degradation at the hands of Israelis? Poverty perhaps? But there is no excuse for murder.

As I write these words the world is on fire almost everywhere. The news is almost universally awful. From Russian-destroyed airliners and bodies strewn over the Ukraine to the rise of blood-thirsty butchers like ISIS and Boko Haram, the world situation is dispiriting and depressing.

Presiding over all of it is the most powerful man in the world, who seems to have checked out.

President Barack Obama is a moral man with clear moral sensibilities. But the pivotal shortcoming of his foreign policy is a failure to revile evil.

When he speaks about the worst kind of human rights abuses he uses vague, technical language and avoids definitive moral statements. He refuses to call Hamas or Boko Haram evil. Why the reluctance to make declarative statements of an absolute nature? Because moral ambiguity can justify inaction.

Iran has threatened a second holocaust on countless occasions. These are not idle words.

It acts on the threat both by funding Hezbollah’s and Hamas’s efforts to murder Jews and, much more ominously, by being on the threshold of attaining nuclear weapons that can kill millions with a single detonation.

Yet in the coolness and detachment of the president’s pragmatism toward Iran and the extension he has just offered it in the nuclear negotiations you might think he was haggling over a trade deal with Switzerland. You would not know that he was speaking about a regime that machine-gunned its own citizens in the streets when they protested a stolen election in 2009, stones women to death and hangs homosexuals from cranes.

President Obama’s reluctance to use the word “terrorism” has been much discussed.

In 2009 his administration formally retired the phrase “War on Terror” and replaced it with the evasive and euphemistic “Overseas Contingency Operations.”

After the deadly terrorist attack at a Kenya mall this past September President Obama said, “We stand together with Kenya in our resolve to confront and defeat violent extremism.”

Violent extremism? Perhaps this would explain Secretary of State John Kerry’s willingness to pressure Israel into a cease-fire with Hamas that would leave much of its terror infrastructure in place.

It’s absolutely horrible seeing Palestinian children dying in Gaza. But the president has to come out clearly and say he loathes the cowardly terrorists of Hamas who continue to use these children as their shields.

To be sure, President Obama and John Kerry are friends of Israel. I will not join the chorus of those who attempt to assassinate the characters of these two men who have done much for Israel. So why is there a perception that their sympathies lie elsewhere? Because they don’t seem to get, and do not state definitively, that Israel is in a moral battle of good versus evil.

Hamas is evil incarnate. It is a menacing, death-glorifying, woman-hating, gay-murdering, anti-Semitic death cult. It has no redeeming qualities.

President Reagan said of the Soviet Union in March 1983: “They are the focus of evil in the modern world.” He implored his audience not “to ignore the facts of history and the aggressive impulses of an evil empire...

and thereby remove yourself from the struggle between right and wrong and good and evil.”

In the end, it was Martin Luther King who summed it up best: “He who passively accepts evil is as much involved in it as he who helps to perpetrate it. He who accepts evil without protesting against it is really cooperating with it.”

Tolerating the intolerable and forgiving the unforgivable is the surest way to empower evil. And if Hamas is not evil, then the word has no meaning.

President Obama can salvage so much of his legacy on foreign policy by beginning to employ the language of moral absolutes, especially when it comes to terror organizations that celebrate the murder of civilians.

Mr. President, the world is watching. History is taking note. Will you call Hamas evil?

The author, “America’s rabbi,” whom The Washington Post calls “the most famous rabbi in America,” is the international best-selling author of 30 books, including The Fed-up Man of Faith: Challenging God in the Face of Tragedy and Suffering.

Follow him on Twitter @ RabbiShmuley.

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